To prevent accumulation of air in a mounting hole upper end part, always ensure a normal functioning condition of a hydraulic tensioner, in a chain tension giving device fixedly fitting a cylinder main unit of the hydraulic tensioner into a mounting hole drilled in an engine main unit.

A constitution is formed such that an oil passage 16 crossed partly in an overlapped condition in an upper part of a mounting hole 15 also with one end thereof communicating with an oil gallery 17 the other end closed is provided, pressure oil is supplied into a cylinder main unit through the oil passage 16 from the oil gallery 17. This oil passage 16 is formed to tilt upward diagonally toward one end communicating with the oil gallery 17, so that air passes through the oil passage 16 to escape in the oil gallery 17.