相纸（英语：Photographic paper），也称照相纸、晒相纸、感光纸指覆以化学感光材料用以印制相片的特殊纸张。用以印制数码照相机的相纸不含化学感光材料成为印相纸。

自从1824年法国尼埃普斯和1841年英国威廉·亨利·福克斯·塔尔博特发明摄影术后，相纸的应用就开始了。时至今日相纸的应用十分普遍。

Photographic paper is a paper coated with a light-sensitive chemical formula, used for making photographic prints. When photographic paper is exposed to light it captures a latent image that is then developed to form a visible image, with most Printing out Papers the image density from exposure can be sufficient to not require further development, aside from fixing and clearing, though latent exposure is also usually present. The light-sensitive layer of the paper is called the emulsion. The most common chemistry was based on silver salts (the focus of this page) but other alternatives have also been used.