An end cap holder may include a base block and a holding block. The base block may be configured to provide an end cap, which may be at a nozzle of the gas cylinder, with a torque for combining/separating the end cap with/from the nozzle. An angle correction groove may be formed at a first surface of the base block oriented toward the end cap. The holding block may be rotatably receivable in the angle correction groove to hold the end cap. The holding block may selectively make point contact with the base block to transmit the torque of the base block to the end cap. Thus, the holding block may accurately hold the end cap tilted to a vertical axis or a horizontal axis.