A filter press comprising a stationary frame, in which a head member, a movable tail member, an actuator for opening and closing movement of the filter press, and a plurality of filter plates arranged between the head member and the movable tail member are arranged, wherein the filter press further comprises a locking arrangement for locking the movable tail member with respect to the stationary frame after the closing movement of the movable tail member and the filter plates towards the head member by said actuator wherein the locking arrangement is arranged to interact with a supporting surface in the stationary frame and a corresponding supporting surface in the movable tail member, characterized in that the locking arrangement comprises at least one locking member having a first wedge-like surface, said at least one locking member is arranged to be movable in a direction perpendicular to the opening and closing movement of the filter press, wherein the first wedge-like surface of the at least one locking member is arranged to interact with a corresponding opposite second wedge-like surface, and at least one locking actuator arranged to move the at least one locking member so that the first wedge-like surface interacts with the opposite second wedge-like surface to thereby press the filter plates against each other, and wherein said corresponding opposite second wedge-like surface is arranged in any one of the supporting surfaces (77, 88) of the stationary frame or the movable tail member, respectively, or wherein the locking arrangement further comprises at least one loading member comprising the opposite second wedge-like surface, which at least one loading member is arranged to be movable in a direction perpendicular to the opening and closing movement of the filter press, and wherein at least one loading actuator is arranged to move the at least one loading member so that the opposite second wedge-like surface of the at least one loading member interacts with the first wedge-like surface of the at least one locking member. at least one locking member having a first wedge-like surface, said at least one locking member is arranged to be movable in a direction perpendicular to the opening and closing movement of the filter press, wherein the first wedge-like surface of the at least one locking member is arranged to interact with a corresponding opposite second wedge-like surface, and at least one locking actuator arranged to move the at least one locking member so that the first wedge-like surface interacts with the opposite second wedge-like surface to thereby press the filter plates against each other, and wherein said corresponding opposite second wedge-like surface is arranged in any one of the supporting surfaces (77, 88) of the stationary frame or the movable tail member, respectively, or wherein the locking arrangement further comprises at least one loading member comprising the opposite second wedge-like surface, which at least one loading member is arranged to be movable in a direction perpendicular to the opening and closing movement of the filter press, and wherein at least one loading actuator is arranged to move the at least one loading member so that the opposite second wedge-like surface of the at least one loading member interacts with the first wedge-like surface of the at least one locking member.