[Problems] To provide a double needle enabling easy centesis in bones and cortex and easy alignment of an inner needle with an outer needle in an angular direction and capable of transmitting torque when the inner needle and the outer needle are rotated simultaneously.[Means for Solving Problems] This double needle (10) for medical treatment comprises the cylindrical outer needle (11) having an edge part (26) at its tip and the solid inner needle (12) detachably stored in the outer needle. When the outer needle (11) is rotated about its major axis, the rotating diameter of the edge part (26) is larger than the rotating diameter of a body part. Also, the double needle comprises a corotation mechanism (20) for the outer needle (11) and the inner needle (12).