An angle adjusting device includes a pedestal, a pair of guide members having an arcuate track, an oscillation body moved along the track of the guide members, and a moving member for moving the oscillation body to adjust the angular position of the oscillation body around an oscillation axis. The moving member has a motor provided in the pedestal, a linkage shaft provided in the oscillation body, and a linkage mechanism interposed between the motor and the linkage shaft. A principal linkage member of the linkage mechanism is linked to a top end portion of an output shaft rotatably around an axis parallel to the oscillation axis, and linked to the linkage shaft to be linearly movable in its axial direction. The guide members have two flat reference planes, and fixed in a state where those reference planes are contact with two flat setting planes of the pedestal.