A vibrationproof device which is a liquid sealed vibrationproof device includes a tubular first mounting member (3) that is connected to either one of a vibration generating portion and a vibration receiving portion, a second mounting member (4) that is connected to other one, an elastic body (5) that elastically connects the first mounting member (3) and the second mounting member (4), and a partition member (8) that partitions a liquid chamber (7) of the inside of the first mounting member (3) into a main liquid chamber (7A) of an upper side having the elastic body as a portion of a wall surface and an auxiliary liquid chamber (7B) of a lower side, and a restricting passage (80) which communicates with the main liquid chamber (7A) and the auxiliary liquid chamber (7B). In addition, a first liquid (L1) is contained as a main liquid and a second liquid (L2) which is insoluble in the first liquid (L1) is contained as an added liquid in the sealed liquid (L), and the vapor pressure of the second liquid (L2) is higher than the vapor pressure of a main component of the first liquid (L1) in the same temperature and a specific gravity of the second liquid (L2) is lighter than a specific gravity of the first liquid (L1).