Image cannot be centered in Hexo blog.

[SightVanish]

My image can be displayed in hexo but cannot be centered.
Here is my code.

<div align="center">
    <img src="./folder/image.jpg"></img>
</div>

However, instead of image, source code is displayed.
What is the cause to this problem? How can I center image?

[renbaoshuo]

<p align="center"><img src="./image.png"></p>

This works for me.

[SightVanish]

WOW, it works for me. Thank you!