下記､
ｶﾃｺﾞﾘｰﾍﾟｰｼﾞ(category.php)のｺｰﾄﾞになります｡

<?php get_header(); ?>

<!--CONTENTS-->
<div id="contents">
<!--MAIN-->
<div class="main" id="archive">

<h2><?php the_category(' // ') ?>の記事一覧</h2>

<?php
foreach((get_the_category()) as $cat) {
$catid = $cat->cat_ID ;
break ;
}
$get_posts_parm = "'numberposts=&category=" . $catid . "'";
?>

<div class="cont">
 <?php $posts = get_posts($get_posts_parm); ?>
 
 <?php foreach($posts as $post): ?>
 <ul class="content2">
 <a href="<?php the_permalink() ?>">
 <li class="img"><?php the_post_thumbnail('thumbnail'); ?></li>
 <li class="title"><?php if(mb_strlen($post->post_title)>25) { $title= mb_substr($post->post_title,0,25) ; echo $title. ･･･ ;} else {echo $post->post_title;}?></li>
<li class="cat"><?php the_category(', ') ?></li>
 <li class="date"><?php the_time('Y年m月j日') ?></li> 
 <li class="text"><?php $text= mb_substr(strip_tags($post-> post_content), 0, 80); echo $text. '...'; ?></li></a>
 <a href="<?php the_permalink() ?>"><li class="read">続きを読む&#9654;</li></a>
 </ul>

<?php endforeach; ?>
</div>

<?php wp_pagenavi(); ?>
 
 <div class="readall">
 <a href="<?php echo home_url(); ?>"><p>すべての記事を見る</p></a>
 </div>




</div>

<?php get_sidebar(); ?>
<?php get_footer(); ?>