A roll sheet image forming apparatus includes an introduction opening and a guide plate. Instead of a continuous sheet held in an apparatus main body, a continuous sheet for option feeding provided at an outside is introduced into the apparatus main body through the introduction opening. The guide plate is for splicing a lead sheet and a continuous sheet. When feeding the continuous sheet, a feeding unit is pulled out from the apparatus main body, a lead sheet is set to be conveyable towards an image forming unit, the feeding unit is again accommodated in the apparatus main body, a front end of the continuous sheet is placed on the guide plate, a rear end of the lead sheet is placed on the guide plate through the introduction opening, the rear end and the front end are spliced by a bonding member and then the feeding unit operates.