Deformation of a second optical carriage (B) due to heat is large on a (C) side where an inverter (31) is attached and small on a (D) side. A mirror supporting portion inside the second optical carriage (B) supports the mirror at one point on the (C) side and at two points on the (D) side. An angle of the reflecting mirror (8) depends on two protrusions on the (D) side where thermal deformation is small, and the mirror is supported at one point on the (C) side where thermal deformation is large. Thus, even if an angle of the mirror supporting portion (C) changes, the angle of the reflecting mirror (8) is not affected. Therefore, a change in the angle of the reflecting mirror (8) can be controlled to be small when temperature of the second optical carriage (B) rises during a reading operation, and decrease in reading accuracy due to thermal deformation of the second optical carriage (B) can be suppressed.