or separating the inner body 105 b and the outer body 105 a is explained as follows if the hydraulic pressure is supplied into the pin groove 202 through the hydraulic pressure gap adjustment device 130 the front end portion of the latching pin 220 is inserted into the spring groove 203 accordingly the latching pin 220 is disposed along the spring groove 203 and the pin groove 202 and if the cam 205 pushes the roller 120 downwards the inner body 105 b and the outer body 105 a rotate based on the hydraulic pressure gap adjustment device 130 to push the valve 140 downwards further if the hydraulic pressure is not supplied to the pin groove 202 through the hydraulic pressure gap adjustment device 130 the guide 210 pushes the latching pin 220 by the return spring 200 such that the latching pin 220 is inserted into the pin groove 202 and the inner body 105 b and the outer body 105 a are separated and if the cam 205 pushes the roller 120 downwards the inner body 105 b rotates in a clockwise based on the hinge 115 such that the outer body 105 a does not move accordingly the valve 140 does not move and an intake stroke a compression stroke an explosion stroke or an exhaust stroke is deactivated it is desirable that the front end surface 304 of the inner body 105 b and the inner side surface 302 of the outer body 105 a contact to slide with regard to each other in an exemplary embodiment of the present invention and the front end surface 304 and the inner side surface 302 are formed in a fan shape along a circle based on a center of.