The invention relates to a mass-decoupling device for a motor vehicle, having: a mass-receiving element (10) and a mass object (11) accommodated therein, which mass-receiving element (10) and mass object (11) are point symmetrically formed and mounted opposite a body (36) of the motor vehicle; at least one guide means (13) that moveably mounts the mass-receiving element (10) and the mass object (11) accommodated therein along a longitudinal axis (L) of the vehicle; decoupling means (14) designed to decouple the mass-receiving element (10) and the mass object (11) accommodated therein from the body (36) of the motor vehicle; first energy-receiving means (15) designed to transmit kinetic energy of a movement of the mass-receiving element (10) and the mass object (11) accommodated therein to the body (36) of the motor vehicle in a predetermined time interval, said movement occurring along the longitudinal axis (L) of the vehicle, from a first position (P1) to a second position (P2); and second energy receiving means (16) designed to convert, at least partially, the kinetic energy of the movement of the mass-receiving element (10) and the mass object (11) accommodated therein along the longitudinal axis (L) of the vehicle into kinetic energy of a rotation of the mass object (11). The invention also relates to a corresponding method for decoupling mass for a motor vehicle.