A sensitivity adjustment device adjusts radio wave sensitivity of an antenna which wirelessly transmits/receives a signal to/from an external device. The sensitivity adjustment device includes: a sensitivity adjuster and an adjuster moving section. The sensitivity adjuster includes (a) a shielding part which shields a radio wave and (b) a penetration part which allows penetration of a radio wave. The adjuster moving section moves the sensitivity adjuster with respect to the antenna in such a way as (a) to change a position of the shielding part and a position of the penetration part with respect to the antenna, and (b) to adjust a covered area of the antenna covered with the sensitivity adjuster, so as to adjust the radio wave sensitivity of the antenna.