PURPOSE: To generate a synchronizing signal without complicating a device by making the device larger and decreasing the power of a light for reading at the time of reading by respectively using a light for recording at the time of reading and the light for reading at the time of reproducing as a light for synchronizing.

CONSTITUTION: At the time of reading an image, the light for recording 2A functions as the synchronizing light of the light for reading 1A and the synchronous change of the light quantity of the light for reading 2A is detected by a light detection unit 12. The change of light quantity is converted into an electrical pulse signal by a synchronizing signal generation means and then the synchronizing signal showing the position of the main scanning direction of the light for reading 1A can be obtained. At the time of reproducing the image, the light for reading 1A is made incident on a grid 10 as synchronous light and detected by the light detection unit 12, so that the synchronizing signal showing the main scanning position of the light for recording can be obtained at the time of reproducing. Thus, the synchronizing signal can be excellently generated at the time of reading and at the time of reproducing without complicating the device by making the cost of the device high and decreasing the power of the excitation light at the time of reading.