A walker - for supporting a walking or standing person by two handles, - comprising a frame with an unlocking mechanism and a locking mechanism, - wherein the two handles are attached at the frame on the lefthand and righthand sides thereof as viewed in a straight-ahead direction of travel in a proper position of the walker, - comprising four wheels (8, 9), respectively attached to the frame in such a way that they all roll on a flat floor in a proper orientation of the walker, and two of which are designed as pivoting wheels, and two wheels, namely the two rear wheels, which are not pivotable, define the straight-ahead direction of travel of the walker, wherein all the wheels (8, 9) are designed as pivotable wheels by enabling the two non-pivotable wheels to become pivotable by executing the unlocking mechanism, namely by being lockable by means of the detachable locking mechanism, which is in the angular position that defines a particular straight-ahead direction of travel of the walker, wherein both lockable wheels are detachable together by using a lever, and said handles form said lever, and are essentially horizontal in the proper position of the walker, and project backwards against the straight-ahead direction of travel, and can be pivoted upwards for detaching. - for supporting a walking or standing person by two handles, - comprising a frame with an unlocking mechanism and a locking mechanism, - wherein the two handles are attached at the frame on the lefthand and righthand sides thereof as viewed in a straight-ahead direction of travel in a proper position of the walker, - comprising four wheels (8, 9), respectively attached to the frame in such a way that they all roll on a flat floor in a proper orientation of the walker, and two of which are designed as pivoting wheels, and two wheels, namely the two rear wheels, which are not pivotable, define the straight-ahead direction of travel of the walker, wherein all the wheels (8, 9) are designed as pivotable wheels by enabling the two non-pivotable wheels to become pivotable by executing the unlocking mechanism, namely by being lockable by means of the detachable locking mechanism, which is in the angular position that defines a particular straight-ahead direction of travel of the walker, wherein both lockable wheels are detachable together by using a lever, and said handles form said lever, and are essentially horizontal in the proper position of the walker, and project backwards against the straight-ahead direction of travel, and can be pivoted upwards for detaching. wherein all the wheels (8, 9) are designed as pivotable wheels by enabling the two non-pivotable wheels to become pivotable by executing the unlocking mechanism, namely by being lockable by means of the detachable locking mechanism, which is in the angular position that defines a particular straight-ahead direction of travel of the walker, wherein both lockable wheels are detachable together by using a lever, and said handles form said lever, and are essentially horizontal in the proper position of the walker, and project backwards against the straight-ahead direction of travel, and can be pivoted upwards for detaching.