The required minimum amount of examination site information is acquired, stored, or transmitted without missing an affected area, thus reducing power consumption, reducing the size of a battery disposed in a capsule, and reducing the size of a casing. Provided is a capsule medical device including a casing having a capsule shape a light-detecting section, disposed in the casing, for detecting information about the intensity of light from outside the casing an information-acquiring section for acquiring examination site information from an examination site positioned outside the casing and a determination section for determining whether or not to acquire, store, or transmit, to the outside, the examination site information acquired by the information-acquiring section on the basis of the information about the intensity of the light detected by the light-detecting section.
