To provide a method for manufacturing a small-sized and thin- piezoelectric oscillator by which the mount workability is enhanced.

A lead frame 5 to which an oscillation circuit is integrated is inserted to a lead frame groove 2b of a lower molding die 2, and the oscillation circuit including part of the lead frame 5 is positioned and inserted to a cavity formed by an upper molding die 1 and the lower molding die 2, the dies are tightened and a resin is molded in the molding die for the piezoelectric oscillator. A gate 2d through which the resin is injected is provided to a side face of a metallic sealing pipe of a crystal vibrator 4, an overflow gate 2e is provided to at least either of a lead terminal side and a tip side of the crystal vibrator 4 orthogonal to the gate 2s and a dummy cavity 2f is provided to the outside of the overflow gate 2e.