The fluid power generator is provided. The fluid power generator includes: a first member that has multiple coils; a second member that is rotatable relative to the first member and that has multiple permanent magnets; a rotating member that is mechanically linked with either one of the first member and the second member to rotate by fluid force; and a clearance controller that moves at least one of the first member and the second member to thereby change a clearance between the first member and the second member, wherein the clearance controller changes the clearance in such a manner as to make the clearance smaller after a start of rotation of the rotating member than before the start of rotation of the rotating member.