Method for attaching gear driving part, and internal combustion engine

A method for attaching a gear driving part in which a first gear provided on a front side of a fixation-side member of a gear driving part in a rotatable manner is meshed with a second gear in which a portion of the tooth is exposed from an opening part of a gear case while being phase-aligned with the second gear, and then the fixation-side member is fixed in the gear case, the method comprising:

• a first step of inserting a positioning bolt into a positioning hole of the first gear from a front side and screwing the positioning bolt into a screw hole of the fixation-side member to regulate a phase of the first gear with respect to the fixation-side member;
• and
• a second step of inserting a portion of the bolt protruding to a front side of the first gear into a hole of the gear case and meshing the first gear with the second gear while positioning the fixation-side member in a predetermined phase position of the gear case.