An insertion plug includes:a rotor fixed around a blade, and housed in an insulating plug case;a guide unit in the insulating plug case to guide the rotor around an axis extending in a longitudinal direction of the blade and within a rotation angle of at least 90 degrees between a first rotation position at which the blade becomes substantially parallel with another blade and a second rotation position at which the blade becomes substantially orthogonal to the other blade; anda positioning unit that positions the rotor at the first rotation position or the second rotation position,the blades caused to project from a position corresponding to an AC power source outlet if the rotor is positioned at the first rotation position, andthe blades caused to project from a position corresponding to a DC power source outlet if the rotor is positioned at the second rotation position.