To offer a mechanical seal device which can also act a plastic material as a constitution material of a driving pin, while stably exerting driving pin capability.

The mechanical seal device carries, in parallel to an axial direction, two or more mechanical seals 4 possessing spinning sealing rings 8 fixed to a rotating shaft object 2, and rest sealing rings 9 conserved on a case object 1 movably in an axial direction. All sealing rings 9 are composed so that relative revolution to the case object 1 may be prevented by engaging the concavity 23 formed in the periphery of each sealing ring 9 to one drive bar 24 which is fixed in two or more places on the case object 1. The drive bar 24 is fixed to the case object 1 in two or more places of both ends edges and an intermediate part, and the concavity of each rest sealing ring 9 is engaged with drive bar members 24a and 24b between the fixed support parts concerned.