In a sliding structure for an internal combustion, a cylinder has recesses in a stroke center region. Piston rings have inclined surfaces on an outer circumferential surface, and a lubricating oil flows between the inner wall surface and the outer circumferential surface that relatively move via the inclined surfaces. At any RPM equal to or greater than at idle, a center friction coefficient at the stroke center region through which the piston rings pass at the highest speed is less than a center friction coefficient when no recesses are formed in the stroke center region. Contrarily, at the RPM, an outside friction coefficient when the piston rings pass through a region outside the stroke center region is less than an outside friction coefficient when the recesses are formed in the outside region. As a result, further improved low fuel efficiency is achieved for the dimple liner technique.