A seal structure includes: first and second members defining a hollow internal area of a fluid device; and a seal member fixed to the first member for sealing a gap between the first and second members. The seal member includes a sliding contact member being in sliding contact with a surface of the second member and formed of a resin. The second member includes a resin layer and a resin layer holding structure. The resin layer is formed by sliding the second member on the sliding contact member to transfer the resin forming the sliding contact member onto a sliding contact portion of the surface of the second member at which the second member comes into contact with the sliding contact member. The resin layer holding structure is a porous film formed by electric discharge surface treatment and holds the resin layer in the sliding contact portion.