A vibration control device that can achieve the best vibration control effect within an allowable stroke range of a movable mass includes a controller that calculates at least one of a displacement deviation between a target displacement of a movable mass and a displacement of the movable mass detected by a mass displacement sensor and a velocity deviation between a target velocity of the movable mass and a velocity of the movable mass detected by a mass velocity sensor, and generates a control command for making a motor drive the movable mass on the basis of at least one of the displacement deviation and the velocity deviation. The target displacement and the target velocity are set in a manner that the amplitude of the movable mass becomes constant and that phases thereof are delayed 90 degrees with respect to the vibration of a building.