A sliding mechanism of the present invention includes a cylinder bore having a thermally sprayed iron-based coating and includes a piston with a piston ring covered with a hard coating composed mainly of carbon.
The thermally sprayed coating has diamond abrasive grains.
An area ratio of the diamond abrasive grains to a surface of the thermally sprayed coating is 0.3 to 1.8%, which enables suppressing wear of the piston ring having the hard coating composed mainly of carbon.