To provide a level reference apparatus capable of drastically improving the accuracy and the stability, which relates to the level reference apparatus which is used when construction, building, and mechanical apparatuses are installed.

In the level reference apparatus, a rocking part supported rockably around two orthogonal axes is provided on a base member. A rotational body is provided on the rocking part. The center of gravity of the rotational body is positioned above the intersection point of the two axes. The center of gravity of the overall rocking part including the rotational body is defined on the axial line parallel to the rotational axis of the rotational body on the intersection point of the two axes. A mirror, a sensor, a laser light source, and so forth can be arranged on the base.