// ===========================
// = パンくず =
// ===========================
function mytheme_breadcrumb() {
    	//HOME>と表示
    	$sep = '>';
    	echo '<li><a href="'.get_bloginfo('url').'" >HOME</a></li>';
    	echo $sep;
     
    	//投稿記事ページとカテゴリーページでの、カテゴリーの階層を表示
    	$cats = '';
    	$cat_id = '';
    	if ( is_single() ) {
    		$cats = get_the_category();
    		if( isset($cats[0]->term_id) ) $cat_id = $cats[0]->term_id;
    	}
    	else if ( is_category() ) {
    		$cats = get_queried_object();
    		$cat_id = $cats->parent;
    	}
    	$cat_list = array();
    	while ($cat_id != 0){
    		$cat = get_category( $cat_id );
    		$cat_link = get_category_link( $cat_id );
    		array_unshift( $cat_list, '<a href="'.$cat_link.'">'.$cat->name.'</a>' );
    		$cat_id = $cat->parent;
    	}
    	foreach($cat_list as $value){
    		echo '<li>'.$value.'</li>';
    		echo $sep;
    	}
     
    	//現在のページ名を表示
    	if ( is_singular() ) {
    		if ( is_attachment() ) {
    			previous_post_link( '<li>%link</li>' );
    			echo $sep;
    		}
    		the_title( '<li>', '</li>' );
    	}
    	else if( is_archive() ) the_archive_title( '<li>', '</li>' );
    	else if( is_search() ) echo '<li>検索 : '.get_search_query().'</li>';
    	else if( is_404() ) echo '<li>ページが見つかりません</li>';
    }

<div class="mytheme_breadcrumb">
    <?php mytheme_breadcrumb(); ?>
       </div>

/* パンくず */
.mytheme_breadcrumb li {
    font-size: 90%;
    display: inline-block;   
}

<h1 class="archive-title"><?php printf( __( 'Category Archives: %s', 'twentytwelve' ), '<span>' . single_cat_title( '', false ) . '</span>' ); ?></h1>

<h1 class="archive-title"><?php printf( __( 'Tag Archives: %s', 'twentytwelve' ), '<span>' . single_tag_title( '', false ) . '</span>' ); ?></h1>