A mechanical seal (100) includes a sleeve (130) fixed to a rotating shaft (200), wherein the sleeve (130) has: a first annular portion (131) that has a step having an inner diameter and an outer diameter on a sealed fluid (F) side thereof that are larger than those of on an opposite side thereto, an inner peripheral surface of a small diameter portion (131a) on the first annular portion (131) is fitted on the rotating shaft (200), and a stationary ring (110) is disposed on the small diameter portion (131a), a rotating ring (120) is disposed between a large diameter portion (131b) and an inner peripheral surface of the rotating ring (120) is sealed, S2÷S1≦1 is satisfied where S1 is a sliding area between the stationary ring (110) and the rotating ring (120), S2 is a pressure receiving area where the stationary ring (110) receives a pressure effect of the rotating ring (120) due to a pressure of the sealed fluid (F).