METHOD OF MANUFACTURING TUNING FORK TYPE QUARTZ PIECE

PROBLEM TO BE SOLVED: To provide a tuning fork type quartz vibration element for improving symmetry of a cross-sectional shape of a trench portion to be provided at a vibration arm unit, and for making its manufacture easy.SOLUTION: A manufacturing method of the tuning fork type quartz vibration element in which the vibration arm unit has the trench portion GL in a length direction with a structure formed of a base part 111 and the vibration arm part 112 extending from the base part includes: an anticorrosion film forming process of forming an anticorrosion film on a crystal wafer; a patterning process of forming photosensitive resist, then removing the photosensitive resist of a portion which becomes to be the trench portion while leaving the photosensitive resist in a tuning fork shape, then removing the exposed anticorrosion film; and a wet etching process of removing a crystal portion where a crystal wafer is exposed, wherein the anticorrosion film within a portion becoming to be the trench portion is removed in a state of a slanted pattern portion to be slanted is left within the portion becoming to be the trench portion from an edge portion in a length direction of the portion becoming to be the trench portion in the patterning process, then the cross-sectional shape of the trench portion is formed nearly to a V shape by gradually removing a crystal piece owing to the anticorrosion film left at the portion becoming to be the trench portion including the slanted pattern portion in the wet etching process.