{Technical Problem} Provide a mechanical seal that allows for preassembly of its seal members on the stationary side, baffle sleeve, damper, and other related parts at a factory, service center, etc., in a reliable and controlled manner, thereby requiring fewer assembly steps during onsite engineering works. {Solution to Problem} The mechanical seal has a seal ring 9 and a mating ring 10 that faces and slides against the seal ring 9 and either the seal ring 9 or mating ring 10 is supported via a bellows 7 on the equipment interior side of a seal cover 2 installed on a housing 1, while the other rotates together with a rotational shaft 3; and a baffle sleeve 17 or 37 with a roughly L-shaped cross-section is fixed on the equipment exterior side of the seal cover 2 to guide quenching liquid to the sliding surfaces of the seal ring 9 and mating ring 10, where the baffle sleeve 17 or 37 is structurally split into a flange part 21 or 38 and cylinder part 22 or 38.