Provided are a piezoelectric vibrating piece, a piezoelectric vibrator, an oscillator, an electronic device, and a radio-controlled timepiece which can effectively suppress the vibration leakage while maintaining sufficient rigidity of the piezoelectric vibrating piece without making the piezoelectric vibrating piece large-sized. A chamfered portion is formed on corner portions of a connecting portion 21 on a narrow width portion side on both sides in the widthwise direction (Y direction). Due to such chamfered portions, a cross-sectional area (width size) of the connecting portion is gradually reduced toward the narrow width portion from a distal end side (vibrating arm portion side). The chamfered portion may be formed such that an angle θ with respect to side surfaces on both sides of the connecting portion becomes 60° (θ=60°).