To keep a desired phase relation between a movable mass and an object in the case that oscillation of the movable mass is suppressed at both ends of an orbit by arranging a resetting force generation device for generating the resetting force of the movable mass, and springs for stoppers on both ends of the orbit.

An anti-rolling device adapted to a gondola, etc., has a movable mass 21 freely movable along an orbit member 11, and a pair of support members 13A, 13B which support the orbit member 11 it its both ends. Two pairs of wheels 21A, 21B mounted on the movable mass 21 are engaged with orbit grooves 11A, 11B parallely formed on an upper surface 11. Springs 23A, 23B arranged on both sides of the movable mass 21 is installed on the support members 13A, 13B. Resetting force of the movable mass 21 is generated by elasticity of the springs 23A, 23B. Buffer rubbers 15A, 15B and springs 17A, 17B for stoppers are mounted on the support members 13A, 13B.