PURPOSE: To provide a bush type vibration control device capable of varying a spring constant, simple in structure and of a liquid enclosure type.

CONSTITUTION: A three port two direction changeover valve 38 is changed over by a control device 64, and a pipe 40 and a pipe 62 are communicated through to each other. An air cell 30 comes to be at the same pressure as the air, and a diaphragm 26 can be deformed to the side of the air cell 30. Consequently, it is possible to freely expand and contract liquid chambers 20, and rigidity in the direction to communicate the liquid chambers 20 through to each other is lowered. Additionally, in the meantime, when the pipe 40 and an intake manifold 58 are communicated through to each other, an air cell 34 comes to be at negative pressure, and the diaphragm 26 is adhered to concave parts 24 constituting the air cell 30. Accordingly, expansion and contraction of the liquid chambers 20 are constrained, and rigidity is improved.