A printer has a record unit including a record in the form of an endless belt which moves in one direction, a charger for charging the record, an exposure unit for forming an electrostatic latent image on the charged record, a developing unit for converting the latent image into a visual image, a sheet feeder for feeding a record sheet from a stack, as separated one by one, and feeding it into close contact with the record which carries the visual image, a transfer unit for transferring the visual image from the record onto the record sheet, a fixing unit for fixing the transferred visual image on the record sheet, and a delivery unit of delivering the fixed record sheet out of the printer. As a characteristic of the invention, the record unit and the developer unit are detachably mounted together and capable of being slid out of the printer for servicing. The other elements of the printer are disposed around the record unit in a generally U-shaped configuration, so that the record/developer unit can be slid into or out of the hollow portion defined by the U-shaped configuration.