A damper device includes a cylinder, a piston, a seal ring member, and a transmitting portion. The piston includes an annular outer circumferential portion, a first stopper portion, a second stopper portion, and a projecting portion. The projecting portion has an inclined surface which is inclined radially outwards form a side of the second stopper portion towards a side of the first stopper portion. The seal ring member is configured to allow a first chamber to communicate with a second chamber when a portion of the seal ring member which is not restricted by the first stopper portion is deformed in a direction away from the second stopper portion due to friction caused between the seal ring member and the cylinder or a fluid pressure from the second chamber to ride on the inclined surface.