A slit lamp microscope of an embodiment comprises a light source, a pair of slit blades, an actuator, a mechanism, a storage, an operating part and a controller. The light source emits illumination light. The slit blades generate slit light from the illumination light. The actuator generates a driving force. The mechanism changes the interval between the slit blades based on the driving force. The storage stores one or more pieces of interval information each indicating an interval between the slit blades. When a user specifies one from among the one or more pieces of interval information using the operating part, the controller control the actuator such that the interval between the slit blades becomes the interval indicated in the specified interval information.