A tilt sensor capable of detecting more diverse orientations is to be provided. The tilt sensor includes a light emitting element and a plurality of photodetectors, a rolling element, and a hollow portion that accommodates the rolling element so as to allow the rolling element to roll in all of x-, y-, and z-direction, and to locate the rolling element, according to a direction of the gravity, at one of detecting positions including a complete blocking position that inhibits light from the light emitting element from reaching any of the photodetectors, a plurality of partial blocking positions that inhibits the light from the light emitting element from reaching at least one but not all of the photodetectors, and a nonblocking position that permits the light from the light emitting element to reach all of the photodetectors, and two of the detecting positions are each located on a respective end portion of the hollow portion in the x-, y-, and z-direction.