Oscillator device and a manufacturing method thereof, an optical deflector, an image forming apparatus

An oscillating body apparatus comprises an oscillating plate oscillatably supported around a torsion axis by a support portion for a fixing portion and driving the oscillating plate around the torsion axis by a resonance frequency, the oscillating plate having a region forming a groove portion for adjusting a mass of the oscillating plate, and, the resonance frequency being configured to be adjustable by the formation of the groove portion in the region.