Custom labels

The marker (or label) at the head of each list entry is yours to change. Turn the bullet of itemize into a diamond, or the “1.” of enumerate into the Roman “I.” or “(a)” — the key is a handful of macros provided per level. This page covers both the classic route via \renewcommand (itemize’s \labelitemi, and enumerate’s \theenumi and \labelenumi) and the modern, easier label= key of enumitem, showing how they differ and when to reach for each.

Changing itemize markers

itemize’s markers live in the macros \labelitemi, \labelitemii, \labelitemiii, and \labelitemiv, one per nesting level (the i / ii / iii / iv are Roman numerals for levels 1–4). In the standard classes the defaults are: level 1 a solid bullet \textbullet (•), level 2 a bold en-dash (–), level 3 an asterisk \textasteriskcentered (*), and level 4 a centered dot \textperiodcentered (·).

To change the marker for a whole level, redefine the matching macro with \renewcommand, placed in the preamble or just before the scope where you want it. For instance, to make the first level a diamond:

\renewcommand{\labelitemi}{$\diamond$}
\begin{itemize}
  \item この階層の記号は菱形になる
  \item 二つめの項目
\end{itemize}

To change the marker for just one entry, give a label in square brackets right after \item. \item[$\star$] makes that entry’s marker a star, and \item[--] a dash. A bracketed label like this is set bold and flush right by default.

enumerate numbers — the counter and \theenumi

enumerate is one notch more involved. Its numbering is driven by a counter per level: enumi, enumii, enumiii, enumiv. How each counter’s value (1, 2, 3 …) is represented is decided by \theenumi, \theenumii, and so on, whose defaults in the standard classes are:

To set the first level in Roman numerals, redefine \theenumi with \Roman. Because \theenumi is also **the string produced when you \ref such an item**, changing it updates the printed number and the cross-reference together (more on references below).

\renewcommand{\theenumi}{\Roman{enumi}}
\begin{enumerate}
  \item 第一段階（既定では I. と表示）
  \item 第二段階
\end{enumerate}

\labelenumi versus \theenumi

This is the crux. Where \theenumi fixes the representation of the number (1 vs I vs a), the macros \labelenumi, \labelenumii, … fix how the label is printed at the head of the line. \labelenumi calls \theenumi internally and wraps it with punctuation (a period or parentheses). The standard-class defaults below add a period everywhere except level 2, which is parenthesized:

So when you want to change only the look of the label (leaving the number’s representation alone), redefine \labelenumi. To turn “1.” into “(1)”, for example, write the following. Since \theenumi is untouched, a \ref to the item still yields a bare 1 without parentheses.

\renewcommand{\labelenumi}{(\theenumi)}
\begin{enumerate}
  \item 行頭は (1) と表示される
  \item (2)、(3) と続く
\end{enumerate}

In short: **the number’s appearance (I, a, 1) is \theenumi; the label’s overall styling (surrounding parentheses or period) is \labelenumi.** The cross-reference value uses the bare representation in \theenumi without the label’s punctuation — more precisely, LaTeX builds the reference by prefixing \theenumi with \p@enumi (empty by default). Define \p@enumii and friends and you can make references that include the parent number, like “1(a)”.

Counter-representation commands

To choose how a number looks inside \theenumi or \labelenumi, use LaTeX’s standard counter-representation commands. Each takes a counter name as its argument (e.g. \Roman{enumi}) and prints that counter’s value in the chosen form.

\alph and \Alph error past 26, and \fnsymbol errors outside 1–9. For example, \renewcommand{\theenumi}{\Alph{enumi}} sets the first level to A, B, C …, while \renewcommand{\labelenumi}{\arabic{enumi})} gives a label like “1)”.

The modern, easy way — enumitem’s label=

Redefining macros is powerful, but it gets unwieldy when you want different styling per list. For most cases the **enumitem package** is cleaner, so reach for it first. Load enumitem and you can set a list’s label right in its optional argument with label=.

Inside label= you use starred representation commands — \alph*, \Alph*, \arabic*, \roman*, \Roman* — which take no argument and stand for the current level’s counter. You write the punctuation alongside, so label=(\alph*) gives “(a)” and label=\Roman*. gives “I.”.

\usepackage{enumitem}
% ...
\begin{enumerate}[label=(\alph*)]
  \item ラベルは (a) になる
  \item (b)、(c) と続く
\end{enumerate}

It works for itemize too — \begin{itemize}[label=$\star$] gives the marker directly. By default label= also sets the form of the **cross-reference (\ref)**, but when you want the reference shaped differently, use the ref= key. For instance [label=(\alph*), ref=\alph*] prints “(a)” at the head while \ref returns a bare “a”. There is also label*=, which appends to the parent label to build accumulated numbers like 1., 1.1., 1.1.1. …

To apply the same styling to every list in the document, set it once with \setlist, naming the kind (itemize / enumerate) and the level in square brackets.

\usepackage{enumitem}
\setlist[enumerate,1]{label=\Roman*.}   % 第1階層を I. II. III.
\setlist[enumerate,2]{label=(\alph*)}    % 第2階層を (a) (b)
\setlist[itemize,1]{label=$\diamond$}    % itemize 第1階層を菱形に

With enumitem’s shortlabels option you can also use the terse, enumerate-package-style syntax such as \begin{enumerate}[(1)]. Finer per-level counter work and inline lists are covered further on the enumitem page.

A worked example

Finally, here is everything in one document. The first half uses the classic route to give the top level a Roman “I.” style; the second reaches the same result tersely with enumitem’s label=. Both produce identical output.

% --- 古典的な方法 / the classic way ---
\renewcommand{\theenumi}{\Roman{enumi}}
\renewcommand{\labelenumi}{\theenumi.}
\begin{enumerate}
  \item 下ごしらえ        % I. と表示
  \item 加熱する          % II.
\end{enumerate}

% --- enumitem を使う / with enumitem ---
\usepackage{enumitem}
\begin{enumerate}[label=\Roman*.]
  \item 下ごしらえ        % I.
  \item 加熱する          % II.
\end{enumerate}

In the first half, \theenumi is set to \Roman to change the representation to I, II, …, and then \labelenumi is defined as \theenumi. to add the period (the default \labelenumi is already \theenumi., so that line is just making the styling explicit). In the second half, the single label=\Roman*. does both jobs at once. For everyday work this enumitem form is enough; only when you need to steer the label and the reference separately do you reach back for \theenumi, \labelenumi, and ref=.