Locomotion device with rollers for travel on a ground, this device comprising: - a sole which extends mainly on a plane known as the "sole plane", and on which at least one of the feet of the user is designed to be supported during use of the device by this user; - at least one roller which is mechanically connected to the sole in order to roll on the ground, this roller being fitted such as to rotate around a rolling axis parallel to the plane of the sole, and also around an axis of pivoting perpendicular to the plane of the sole; - a braking device which can exert a braking torque on the roller, the amplitude of which varies according to a turning angle, the turning angle being the angle between: • a longitudinal axis of the sole, this longitudinal axis being set without any degree of freedom for the sole, and contained on the plane of the sole; and • the orthogonal projection, on the plane of the sole, of the instantaneous direction of displacement of this sole, this braking device comprising: - a pad which can be displaced between an advanced position, in which it exerts pressure on the roller in order to brake it, and a retracted position, in which it does not exert any pressure on the roller, or exerts lower pressure on it; - a mechanism which can transform the pivoting of the roller in a direction around its axis of pivoting into displacement of the pad from its retracted position to its advanced position, and pivoting of the roller in the opposite direction around its axis of pivoting into displacement of the pad from its advanced position to its retracted position, characterized in that this mechanism comprises: - a planetary gear set comprising: • a planetary wheel which is secured without any degree of freedom on the sole, and the axis of revolution of which coincides with the axis of pivoting of the roller; and • a satellite gear (104, 106) which is rotated by the planetary wheel around a rotational shaft which is secured without any degree of freedom on the roller; and - a pin (120, 122) which can be displaced by the satellite gear between: • a close position in which it thrusts the pad and retains it in its advanced position; and • a distant position in which it permits displacement of the pad from its advanced position to its retracted position. - a sole which extends mainly on a plane known as the "sole plane", and on which at least one of the feet of the user is designed to be supported during use of the device by this user; - at least one roller which is mechanically connected to the sole in order to roll on the ground, this roller being fitted such as to rotate around a rolling axis parallel to the plane of the sole, and also around an axis of pivoting perpendicular to the plane of the sole; - a braking device which can exert a braking torque on the roller, the amplitude of which varies according to a turning angle, the turning angle being the angle between: • a longitudinal axis of the sole, this longitudinal axis being set without any degree of freedom for the sole, and contained on the plane of the sole; and • the orthogonal projection, on the plane of the sole, of the instantaneous direction of displacement of this sole, • a longitudinal axis of the sole, this longitudinal axis being set without any degree of freedom for the sole, and contained on the plane of the sole; and • the orthogonal projection, on the plane of the sole, of the instantaneous direction of displacement of this sole, - a pad which can be displaced between an advanced position, in which it exerts pressure on the roller in order to brake it, and a retracted position, in which it does not exert any pressure on the roller, or exerts lower pressure on it; - a mechanism which can transform the pivoting of the roller in a direction around its axis of pivoting into displacement of the pad from its retracted position to its advanced position, and pivoting of the roller in the opposite direction around its axis of pivoting into displacement of the pad from its advanced position to its retracted position, - a planetary gear set comprising: • a planetary wheel which is secured without any degree of freedom on the sole, and the axis of revolution of which coincides with the axis of pivoting of the roller; and • a satellite gear (104, 106) which is rotated by the planetary wheel around a rotational shaft which is secured without any degree of freedom on the roller; and • a planetary wheel which is secured without any degree of freedom on the sole, and the axis of revolution of which coincides with the axis of pivoting of the roller; and • a satellite gear (104, 106) which is rotated by the planetary wheel around a rotational shaft which is secured without any degree of freedom on the roller; and - a pin (120, 122) which can be displaced by the satellite gear between: • a close position in which it thrusts the pad and retains it in its advanced position; and • a distant position in which it permits displacement of the pad from its advanced position to its retracted position. • a close position in which it thrusts the pad and retains it in its advanced position; and • a distant position in which it permits displacement of the pad from its advanced position to its retracted position.