To provide a mechanical seal which can give a strong quenching function by increasing the supply pressure or supply volume of quenching fluid, and can give an excellent sealing function even for slurry fluid.

A cartridge type mechanical seal is composed of a stationary side sealing element (3) composed of a seal case (8) and a group of members to be fixed to the seal case (8), and a rotary side sealing element (4) composed of a sleeve (22) which is inserted and fixed to a rotary shaft (2) and a group of members to be fixed to the sleeve (22), so as to be integrally connected by means of dismountable setting jaws (7). A secondary sealing member (6) for sealing a quenching chamber (5) and an outside region (B) gives a sealing function by a relative rotary sliding function between a movable sealing ring (40), which is movably held in the axial direction by one of a seal case (8) and the sleeve (22), and a fixed sealing ring (41) fixed to the other of the seal case (8) and the sleeve (22).