Decompression device for internal combustion engine

A decompression device for an internal combustion engine having a valve timing mechanism including a rocker arm that receives a driving force from a cam to operate a valve in an opening direction, a valve spring that exerts a reaction force on the valve toward a closing direction, and a lash adjuster that forms a fulcrum of the rocker arm, the decompression device comprising:

• a positioning member that is inserted into a swing range of an end portion of the rocker arm, on a side which is supported by the lash adjuster, when the rocker arm has been inclined toward a direction in which the valve is opened, comes into contact with the end portion of the rocker arm when the rocker arm is inclined toward a direction in which the valve is closed, and thereby restricts the rocker arm from returning to a position at which the valve is completely closed;
• and
• an actuator configured to perform an operation of inserting the positioning member into the swing range, and an operation of pulling out the positioning member from the swing range.