The purpose of the present invention is to provide a mechanical seal in which a stationary-side sealing ring can follow the movement of a rotating-side sealing ring to provide reliable sealing properties and by which the entire device can be made compact.A mechanical seal in which a rotating-side sealing ring 13 attached to a shaft 2 and a stationary-side sealing ring 21 attached to a housing 3 slide relative to each other and seal between the housing 3 and the shaft 2 includes a case 22 which is attached to the housing 3 and which contains the stationary-side sealing ring 21, and a seal member 23 which is disposed between the case 22 and the stationary-side sealing ring 21, and the case 22 includes a holding part 22d which regulates the seal member 23 from moving to both sides in the axial direction thereof.