An object of the present invention is to provide a crystal oscillator piece in which the generation of leakage vibration is suppressed, and a method for manufacturing such a crystal oscillator piece. More specifically, a method for manufacturing a crystal oscillator piece according to the present invention includes the steps of forming a first etching mask on an upper surface of a crystal wafer and a second etching mask on a lower surface of the crystal wafer, and forming a vibrating tine by immersing the crystal wafer in an etching solution thereby dissolving crystal portions not covered with the first and second etching masks, wherein the second etching mask is designed to have a first protruding portion protruding from a position corresponding to a first edge of the first etching mask, the first protruding portion being chosen to have such a length that a first residue is formed in a predetermined shape on a first side face, irrespective of a positional displacement between the first and second etching masks, and wherein the first and second etching masks are designed so that a second residue formed on a second side face is adjusted so as to ensure that one of two principal axes passing through a centroid and dynamically perpendicular to each other in a cross section taken perpendicularly to a longitudinal direction of the vibrating tine is oriented substantially parallel to the upper or lower surface of the crystal wafer.