Disclosed is a microcoil assembly. The microcoil assembly includes: a microcoil unit inserted into a patients body in which an aneurysm or other vascular malformation has occurred to induce blood clotting, thereby preventing blood from flowing a coil pusher unit disposed adjacent to the microcoil unit to transfer the microcoil unit to the region of the patients body where the aneurysm or other vascular malformation has occurred an extension wire disposed on the coil pusher unit so as to be movable relative thereto a bundle string connected to the microcoil unit and the extension wire and a bundle string cutting unit disposed adjacent to the coil pusher unit so that at least one portion thereof is movable between a setting position at which the bundle string is maintained in a tied state and a cutting position at which the bundle string is cut in order to cut the bundle string when the bundle string cutting unit moves to the cutting position.
