To provide a seal structure for a high-pressure pump that can protect a seal ring used to seal a valve in a high-pressure pump against filling a housing groove even if swelling and against wear by pressure pulsation.

A seal ring 72 has a movement regulating portion 72b continuous with a seal portion 72a to fill the complete width of a seal ring housing groove 64d. Movement of the seal ring 72 due to pressure pulsation is precluded in a width direction to protect the seal ring 72 against wear. The movement regulating portion 72b forms a sufficient clearance 74 to the inner circumference of a housing recess 14b. Even if swelling, the seal ring 72 can be protected against filling the seal ring housing groove 64d and against deformation and breakage resulting from an intrusion of part of the swelling seal portion 72a into a gap between a cylindrical portion 64b of a lower seat body 64 and the housing recess 14b.