An exemplary tuning-fork type piezoelectric vibrating piece has at least a pair of vibrating arms extending from one end of a base portion in a certain longitudinal direction (e.g., Y-direction). Supporting arms extend from respective side edges of the base, outboard of the vibrating arms in the certain direction. The supporting arms have respective mounting regions near their distal tips. Each supporting arm progressively narrows from its proximal end, coupled to the respective side edge of the base, to its respective mounting region. The progressive narrowing can be via one or more constrictions along the length of the supporting arm.