A camshaft apparatus includes rolling bearings which support a camshaft rotatably, whereby a reduction in torque when an engine is started or is running at low speeds, a reduction in vibration of the camshaft and an extension of the lives of the bearings can be realized. In the rolling bearings, one rolling bearing is made to constitute a main ball bearing which restrains an axial relative movement of the camshaft relative to a shaft case, and the other rolling bearings are made to constitute a plurality of needle roller bearings, whereby a mechanical movement of the camshaft in an axial direction can be restricted in an ensured fashion by the main ball bearing. As to relative displacements due to thermal expansion or contraction of the camshaft and/or the shaft case, an axial relative displacement can be absorbed by needle rollers relatively moving on inter-cam outer circumferential surface areas.