[Problem]
To provide an internal combustion engine for a saddle-ride type vehicle configured to improve assemblability and productivity.
[Solution]
An internal combustion engine 31 for a motorcycle 10 includes a rear cylinder head 97, the rear cylinder head 97 being provided with a camshaft 104, an exhaust rocker arm 107 rocked by the camshaft 104, an engine valve closed/opened by being push-pressed by the exhaust rocker arm 107, and a rocker arm shaft 108 swingably supporting the exhaust rocker arm 107. In the internal combustion engine 31 for the motorcycle 10, the rear cylinder head 97 is provided separately from a holder member 98, the holder member 98 being provided adjacently to the rear cylinder head 97, the camshaft 104 is rotatably supported by the holder member 98, and the holder member 98 is provided with right and left rear side walls 152u and internal combustion engine supporting portions 152a, the right and left rear side walls 152u supporting the rocker arm shaft 108, the internal combustion engine supporting portion 152a being supported by a vehicle body frame.