To improve a skew correction device in a multiple image forming equipment with multiple scanners.

Scanners have a mirror device 200 which returns incoming light into an optical path between a polygon mirror and a light sensitive body and emits it. The mirror device 200 has a pair of mirrors 220, 222 in a housing 210 and returns incoming light L1 as outgoing light L2. A pivot 230 is provided at one end in the longitudinal direction of the housing 210, and a bracket 242 which is operated with an actuator 240 is provided at the other end. The axis of the pivot 230 is tilted by a prescribed angle in relation to the incoming light L1, and the actuator 240 moves the bracket 242 toward a direction orthogonal to the pivot 230. The makeup helps correct a skew without changing right and left magnifications.