To provide a galvanometer mirror whose initial tilt angle can be made as small as possible and to provide an optical device capable of supplying a playback signal of high reliability by mounting the galvanometer mirror.

A prism mirror 23, which reflects laser light, is supported elastically by a leaf spring 24. Further, coils 25a and 25b are fixed to the prism mirror 23, permanent magnets 29a and 29b face each other across a specific magnetic gap, and the prism mirror 23 is driven with a Lorenz's force. At this time, the prism mirror 23 rotates on the optical axis of an objective. Further, a magnetic body 30 is fixed right in the space part of the coil 25b. The prism mirror 23 can be rotated finely on the optical axis of the objective by finely moving the permanent magnet 29b in X direction, and the initial tilt angle of the prism mirror 23 can be corrected.