To move a pair of side fences to a proper position according to the lateral movement of a sheet feed base without requiring any by a user.

This printer comprises a sheet feed part having a sheet feed base for placing a printing sheet and a sheet feed base moving means capable of moving the sheet feed base orthogonally to a sheet carrying direction, and a sheet discharge part having a discharge base for placing discharged printing sheets and a pair of side fences interfering with the lateral ends of the printing sheet discharged on the sheet discharge base to regulate the placing position orthogonal to the sheet carrying direction. This printer further comprises a sheet feed base position detecting means for detecting the moving position of the sheet feed base and a pair of side fence moving means for moving each of the side fences vertically to the carrying direction by the drive force of each side fence motor, and the side fences are moved to a position corresponding to the moving position of the sheet feed base detected by the feed base detecting means by the respective side fence moving means.