A lamp system (10) includes a straight tube type lamp (13) and a socket (14). The straight tube type lamp (13) includes a straight tube type cover (20) containing a light-emitting element, and caps (23) arranged at both ends of the cover (20). A pair of lamp pins (30) whose tips respectively protrude in directions intersecting a lamp longitudinal direction are protrudingly provided on end faces of the caps (23) at both the ends. The socket (14) includes a socket body (41), a rotor (42) which is arranged in the socket body (41) and on which the pair of lamp pins (30) of the straight tube type lamp (13) are mounted, and a pair of terminals to which the pair of lamp pins (30) mounted on the rotor (42) are connected. At least the rotor (42) can move in the lamp longitudinal direction.