A connector comprises an upper surface finger-resting portion that extends in the longitudinal axial direction on the outer periphery of the gripping portion, and on which the first finger is placed, a lower surface finger-resting portion on which the second finger or the third finger is rested when the connector is gripped by placing the first finger on the upper surface finger-resting portion, and a guide protrusion portion that is arranged on the same straight line as the upper surface finger-resting portion in the longitudinal axial direction and determines the position to be inserted, in which the connector is directly fitted into the receiving-side connector by directing the finger tip of the first finger that is placed on the upper surface finger-resting portion to the guide groove of the receiving-side connector and inserting the connector.
