Abstract: A straight tube luminaire, detachably attached between one pair of opposed rotary sockets, includes one pair of connection terminals electrically connected to each of the pair of rotary sockets within a predetermined rotational range of the rotary sockets, one pair of straight tube illumination sockets electrically connected to the connection terminals and electrically connected to electrodes provided at both ends of a rectilinear fluorescent lamp, and a reflective plate extended between the pair of straight tube illumination sockets and attached to the straight tube illumination sockets to reflect light of the fluorescent lamp. The reflective plate and the straight tube illumination sockets are rotated as one body together with the connection terminals by inserting the connection terminals into the rotary sockets and rotating the rotary sockets.