A guidewire includes a core shaft having a front end portion and a rear end portion, a helical coil in which the front end portion is inserted, and a solder part with which the front end portion and the helical coil are bonded to each other. The helical coil is formed of a wire having a plurality of grooves in a surface of the wire, the grooves being formed such that more grooves are formed along an axial direction of the wire than along a circumferential direction of the wire.
