A door opening and closing device opens and closes a slide door of a vehicle in cooperation with a guide roller unit affixed to the slide door. The guide roller unit is provided with a guide member and a belt-side bracket which is joined to the guide member. The door opening and closing device is provided with: a resin support member; pulleys supported by the support member; and a transmission belt wrapped about the pulleys. The support member is affixed to the body of the vehicle and has a rail section to which the guide member is mounted. The belt-side bracket is affixed to the transmission belt. An electrical drive source moves the transmission belt so that the slide door is opened and closed while the guide member is guided along the rail section. The support member has an engagement section capable of holding the belt-side bracket.