Disclosed is a firearm having dual barrels comprising a firearm body which is equipped with a small caliber barrel and a large caliber barrel; a selector installed on one side of the firearm body to select the type of bullet and the mode of firing; a fire control system installed on the firearm body to enable aiming the target through detecting the target both at day and night time; a firearm switch unit installed on the firearm body to transmit the information on the firing of the bullet; a fuse setter installed on the firearm body to transmit the control signal of the fire control system to the fuse of the explosive bullet which is introduced into the large caliber barrel; and a sensor device unit installed on the firearm body to transmit the position of the selector and sensed firing signal to the fire control system.