It is hypothesized that the sliding surface structures improve the lubrication condition by forming an oil sump on the sliding surface, redistributing the oil, and trapping wear debris. For these reasons, the sliding surface structures have been used as a friction reduction method for a long time. However, how to optimize the sliding surface structure is still controversial. In this work, effects of microstructure laid on the cylinder liner of an internal combustion engine on twin-land oil control ring (TLOCR) and piston skirt lubrication condition were investigated by comparing friction between the conventional fine-honed liner (CFL) and the microstructured liner (MSL) which was made based on the CFL. As a result of the friction measurement using a floating liner engine, it was found that the microstructure improved lubrication condition by reducing hydrodynamic friction. On the other hand, the result showed there was a possibility that the microstructure deteriorated friction depending on the engine operating conditions.