A pressure-relief valve is provided. The pressure-relief valve having a valve body with a passage that can be closed by a moving closure element. An electromagnet is mounted detachably on the valve body and interacts with an armature in driving connection with the closure element. A spring interacts with the closure element the bias tension of which can be changed by an adjustment element that can be moved manually relative to the valve body. The adjustment element and the valve body are constructed such that a manual change of the bias tension of the spring by means of the adjustment element is then possible only when the electromagnet is detached from the valve body. Also provided is a round baler employing such a pressure-relief valve.