A printer includes a body, a lid pivotably attached to the body, a platen roller attached to the lid, and a lock lever. The body includes a print head and a holder to accommodate a roll of recording sheet. The lock lever supports a bearing of the platen roller when the lid is closed. The printer further includes a first plate and a second plate arranged on the lid in the widthwise direction of the printer, and a movable button provided on the lid. When the button is moved to slide the first and second plates toward each other, the outer end of each of the first and second plates in the widthwise direction moves inward to be positioned inside the outer frame of the holder to allow the closure of the lid.