<?php
// 親カテゴリーのものだけを一覧で取得
$args = array(
'parent' => 0,
'orderby' => 'term_order',
'order' => 'ASC'
);
$categories = get_categories( $args );
?>
<?php foreach( $categories as $category ) : ?>
<li>
<a href="<?php echo get_category_link( $category->term_id ); ?>"><?php echo $category->name; ?></a>
</li>
<?php endforeach; ?>