Edit in JSFiddle

img{
   width:100%;
    height:auto;
  
}

.sample{
    position:relative;
    background:#fff;
    width:60%;
    padding:10px;
    margin:0 auto;
}
.sample:before{
   z-index:-1;
    position:absolute;
    content:"";
    bottom:10px;
    left:10px;
    width:50%;
    top:80%;
 
    background:#8d8c8c;
     -webkit-box-shadow:0 15px 10px  #8d8c8c;
    -moz-box-shadow:0 15px 10px #8d8c8c;
    box-shadow:0 15px 10px #8d8c8c; 
     -webkit-transform:rotate(-5deg);
    -moz-transform:rotate(-5deg);
    -o-transform:rotate(-5deg);]
    -ms-transform:rotate(-5deg);
    transform:rotate(-5deg);

    
}


.sample:after{
   z-index:-1;
    position:absolute;
    content:"";
    bottom:10px;
    right:10px;
    width:50%;
    top:80%;
   
    background:#8d8c8c;
    -webkit-box-shadow:0 15px 10px #8d8c8c;
    -moz-box-shadow:0 15px 10px #8d8c8c;
    box-shadow:0 15px 10px #8d8c8c;
    -webkit-transform:rotate(5deg);
    -moz-transform:rotate(5deg);
    -o-transform:rotate(5deg);]
    -ms-transform:rotate(5deg);
    transform:rotate(5deg);
    
}
<p class="sample"><img src="http://msweb.moo.jp/wordpress/wp-content/themes/d-siori/img/css_img02.jpg" alt="サンプル" width="300" height="200" /></p>