Provided are a sliding member for sealing and a seal device that exhibit good sealing performance even when used in an environment where silicon oxide is likely to be deposited; the sliding member for sealing includes a sintered body consisting of 1.0 to 12.5 wt.% of cerium oxide, a combination of 20 to 50 wt.% of graphite and graphitizable carbon, and a remainder of non-graphitizable carbon; and, the sliding member for sealing is used as, for example, a rotary seal ring or a stationary seal ring.