get_termsとget_postsの入れ子例

page-faq.php

<?php
  $taxonomies = get_terms(
    'faqcategory',array(
        'orderby' => 'slug',
        'order' => 'ASC'
  ));
  foreach($taxonomies as $taxonomy) :
?>
  <div class="parentBox">
    <div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
      <h2><?php echo $taxonomy->name; ?></h2>
      <ul>
        <?php
            global $post;
            $faqposts = get_posts( array (
                'post_type' => 'faq',
                'taxonomy' => 'faqcategory',
                'term' => $taxonomy->slug
                ));
            foreach($faqposts as $post): 
            setup_postdata($post);
        ?>
        <li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
        <?php endforeach; wp_reset_postdata(); ?>
      </ul>
    </div>
  </div><!-- /.parentBox -->
<?php endforeach; ?>