PURPOSE: To provide a seal device Which leads working fluid to a main seal at low pressures at which any damage does not occur on the main seal so as to maintain the performance by lubricating seal members of the main seal, and operates, at high pressures, without transmitting high pressure and impact pressure of working fluid to the main seal.

CONSTITUTION: A protective seal device 6 to seal working fluid is provided with a seal ring, a pressing 12 to provide a contact pressure to a seal ring 11 and a seal ring 11, and an energizing ring 13 to engage with the pressing ring 12. Also the seal ring 11 is provided with a first sliding surface 11a, a second sliding surface 11b, and a flow path 11c on the sliding surface 11b.