A mechanical seal of an “outside type” for sealing a sealed fluid that may leak from an inside periphery of a sliding face towards an outside periphery is provided. The seal includes a rotating-side sealing element and a stationary-side sealing element disposed so as to be situated externally with respect to a stuffing box. The stationary-side sealing element, which accommodates a spring, is installed on a seal cover that is secured to the housing. The rotating-side sealing element is installed on a collar that is installed directly on the rotating shaft. The rotating side, which comprises the rotating-side sealing element and the collar, is positioned such that rotation takes place in the atmosphere on a machine-exterior side. A balance ratio A2/A1 is 1 or less, A1 being an axial-direction projection area of the sliding face of the stationary-side sealing element and A2 being an axial-direction projection area that is subjected to a seal fluid pressure acting as a motive force in the axial direction relative to the stationary-side sealing element. An annular cooling jacket is disposed between an inside periphery of the housing and an outside periphery of the rotating shaft.