A sliding bearing structure for a shaft member includes: a shaft member; a bearing member rotates relative to the shaft member; an oil supply space to which lubrication is supplied between sliding surfaces of the shaft member and the bearing member; two annular grooves formed in a circumferential direction in an inner peripheral surface of the bearing member; and two annular seal members formed as separate pieces from the shaft member and the bearing member, and arranged in the annular grooves between the shaft member and the bearing member. Each annular seal member is formed in plural, and is made of material having a thermal expansion coefficient such that an inside diameter of the annular seal member is smaller than an inside diameter of the bearing member at a low temperature, and is the same as or larger than the inside diameter of the bearing member at a high temperature.