A guidewire is disclosed, which includes a core member that is an elongated member having flexibility, and a coil member that is disposed so as to cover a distal portion of the core member and that is formed by helically winding a strand, the coil member being fixed to the core member in a distal portion of the guidewire. The core member includes a body portion in a proximal portion thereof and a flat portion in the distal portion thereof. At least one projection is formed on at least one of two side surfaces of the flat portion extending in a longitudinal direction, the at least one projection projecting into a space between adjacent turns of the strand and being in contact with the strand.
