为什么php代码在浏览器中显示？

Question

I have installed node.js and nginx for my web app development, is working fine. Now I have to develop php website with nginx. I have installed php5-fpm on my Ubuntu 14.01 machine, and create one sample index.html and index.php in 'var/www/html/test/' directory. When I enter url for .html page (e.g. '192.168.1.201:3001/index.html', it's looks perfect. but when enter url for .php (e.g. '192.168.1.201:3001/index.php') is shows me code instead of running code. Here is output in my browser :

<?php
  phpinfo( );
?>

I have posted my question here with details. I don't know, why is this happens. No errors logs in nginx or php5fpm. Where to find proble?

Thanks