CAM ANGLE SENSOR ATTACHING STRUCTURE FOR INTERNAL COMBUSTION ENGINE

[Problem to be Solved]It is to provide a cam angle sensor attaching structure for an internal combustion engine capable of enhancing stiffness around a point where a cam angle sensor is attached to suppress vibration of the cam angle sensor to thereby prevent accuracy of detecting a rotational angle of a camshaft from deteriorating.[Solution]An EGR housing portion 25 attached to a cylinder head 4 includes: an upper wall 25D with an attaching boss portion 28A, 28B to which a cam angle sensor 31, 32 is attached, the upper wall being connected to a front wall 25A, a rear wall 25B, and a left side wall 25C; and a tubular EGR passage portion 26 with an EGR passage 26a through which an EGR gas flows, the EGR passage portion being located on the same side as the left side wall 25C. The EGR passage portion 26 includes: an EGR gas inlet 26b provided at the front wall 25A, to introduce the EGR gas into the EGR passage 26a; and an EGR gas outlet 26c provided at the rear wall 25B, to discharge the EGR gas from the EGR passage 26a. The attaching boss portion 28A, 28B is connected to the EGR passage portion 26.