Mechanical seal

An inside-type mechanical seal is mounted between a rotating shaft and a housing, and adapted for preventing leakage of a sealed fluid from an outer circumference of a sliding surface in the direction of an inner circumference thereof, wherein provided are a rotary-side sealing ring mounted on a rotating shaft side, a stationary-side sealing ring mounted on a seal case side, an annular packing for pushing the stationary-side sealing ring toward the rotary-side sealing ring, a holding part on the outer circumferential side being fitted in the seal case, and a seal lip part on the inner circumferential side being in close contact with the stationary-side sealing ring, and wherein provided to the seal case is a ring-shaped projection abutting against a back surface of the packing during assembly of the mechanical seal, and adapted for pushing the packing toward the stationary-side sealing ring.