To make it easy to mount a liquid damper device so that it damps the opening action of a glove box.

The liquid damper device 1 comprises a cylinder sealing silicone oil therein; a piston 5 dividing the inside of the cylinder 3 into a pressure chamber 21 side and a non-pressure chamber 23 side, and having a piston rod 29 movable between the pressure chamber 21 side and the non-pressure chamber side 23 and projecting to the outside of the cylinder 3; a flow passage 25 capable of moving the silicone oil between the pressure chamber 21 side and the non-pressure chamber 23 side by moving the piston 5 between the pressure chamber 21 side and the non-pressure chamber 23 side; and a valve element 27 acting to a closing side to the flow passage 25 when the piston moves to the pressure chamber 21 side, and acting to an opening side to the flow passage 25 when the piston 5 moves to the non-pressure chamber 23 side. When a piston rod 29 expands/contracts to the cylinder 3, the piston 5 moves to the pressure chamber 21 side.