A catheter including a sheath configured to be inserted into a lumen; a drive shaft inserted into the sheath; an image information acquiring unit fixed to a distal end of the drive shaft and acquires image information; a hub which moves the drive shaft in an axial direction of the sheath; an outer tube on a proximal end side of the sheath and includes a first connector at a proximal end thereof; a second connector which includes on a proximal end side of the outer tube a male connector able to be connected to and disconnected from the first connector; and an inner tube on a distal end side of the hub, that moves with respect to the outer tube along with the movement of the hub.