A non-threaded, one-touch connection device for connecting reinforcing bars includes a pair of coupler bodies fastened together by a connector and each of the coupler bodies having a hollow portion for receiving the reinforcing bar. An inner diameter of the coupler body gradually increases from an entrance of the coupler body to an end opposite to the entrance. A lock is placed in the coupler body. The lock includes slits and wall parts partially separated by the slits. The lock further includes a breaking disc configured to break away from the lock. An elastic member is placed between the connector and the lock to apply an elastic force to move the lock toward the entrance when the reinforcing bar is fastened to the lock. The coupler body further has a checking hole to allow concrete to flow in and out.