To provide an intake and exhaust valve driving control device which can suppress flexure deformation of a control shaft, and improve positional accuracy of a control housing.

In this device, a control shaft supporting member 41 which rotatably supports a control shaft 33 is integrated with all cylinders, independently on a cam bracket 13 which rotatably supports a cam shaft 11 to a cylinder head S. A base part 43 of the control shaft support member 41 is firmly fixed to the cylinder head S at its part near an ignition plug attaching hole 46, by means of bolts 47, 48. The control shaft 33 is rotatably supported by means of a bearing part 44 of the support member 41, at the position adjacent to a control housing 18. Even when valve spring repulsion is applied to the control shaft 33 through the control housing 18, flexure deformation of the control shaft 33 can be suppresed because the control shaft 33 is supported at the position adjacent to the control housing 18.