显影罐，用来冲洗照相底片的不透光容器。显影罐多用黑色塑胶制造，也有不锈钢制成的。

显影罐分几种：

A developing tank is a light-tight container used for developing film. A developing tank allows photographic film to be developed in a daylight environment. This is useful because most film is panchromatic and therefore can not be exposed to any light during processing. Depending upon the size and type, a developing tank can hold one to many roll or sheet films.