A pressing device is provided with a pin member, a coil-like spring member, and a spring receiving member which has a through-hole for allowing the pin member to be inserted therein and which supports one end of the spring member. The pin member has: a shaft section which has the spring member disposed on the outer peripheral side thereof; a head section which is interconnected with one end of the shaft section and which can come into contact with the contact surface of the opening/closing body; a spring support section which supports the other end of the spring member; and an engagement claw which engages with the outer surface of the mounting portion and which prevents the pressing device from being dislocated from the mounting portion.