cat_is_ancestor_of
<div class="cat">
<?php
$cats = get_the_terms($post->ID,'koe_chiiki');
//子カテゴリを取得
$current_cat = '';
foreach ($cats as $cat) {
if (!$current_cat || cat_is_ancestor_of($current_cat, $cat)) {
$current_cat = $cat;
}
}
// 子カテゴリを出力
echo $current_cat->name;
?>
</div>
<?php
$cats = get_the_category();
//子カテゴリを取得
$current_cat = '';
foreach ($cats as $cat) {
if (!$current_cat || cat_is_ancestor_of($current_cat, $cat)) {
$current_cat = $cat;
}
}
// 子カテゴリを出力
echo "<a href=".get_category_link($current_cat->term_id).">".$current_cat->name."</a>";
?>