A vibration damping device (1, 10, 100) comprising: a tubular metal bracket (20, 120) which is connected to any one of a vibration generating portion and a vibration receiving portion; a first attachment member (12, 112) which is connected to the other of the vibration generating portion and the vibration receiving portion; a tubular second attachment member (11, 23, 111) which is inserted into the metal bracket (20, 120); an elastic body (13, 113) which connects the first attachment member (12, 112) and the second attachment member (11, 23, 111) to each other; a partition member (17, 117) which partitions a liquid chamber (14, 114) in the second attachment member (11, 23, 111) into a main liquid chamber (15, 115) having the elastic body (13, 113) as a portion of a partition wall and an auxiliary liquid chamber (16, 116); and a diaphragm (19, 119) which constitutes a portion of a partition wall of the auxiliary liquid chamber (16, 116), wherein one of both end opening portions of the second attachment member (11, 23, 111) in an axial direction is closed by the elastic body (13, 113) and the other thereof is closed by the diaphragm (19, 119), wherein a fixing portion (20b, 120b) which fixes the second attachment member (11, 23, 111) is formed on the metal bracket (20, 120), wherein a fixed portion (11g, 23c, 111c) which is fixed to the fixing portion of the metal bracket (20, 120) is formed on the second attachment member (11, 23, 111), wherein a gap (S2, S21) is provided between a portion of an outer circumferential surface of the second attachment member (11, 23, 111) except for the fixed portion (11g, 23c, 111c), and a portion of an inner circumferential surface of the metal bracket (20, 120) except for the fixing portion (20b, 120b), and wherein a second seal portion (22, 123) is provided between the fixed portion (11g, 23c, 111c) and the fixing portion (20b, 120b), characterized in that the gap (S2, S21) is a vacuum sealed space. a tubular metal bracket (20, 120) which is connected to any one of a vibration generating portion and a vibration receiving portion; a first attachment member (12, 112) which is connected to the other of the vibration generating portion and the vibration receiving portion; a tubular second attachment member (11, 23, 111) which is inserted into the metal bracket (20, 120); an elastic body (13, 113) which connects the first attachment member (12, 112) and the second attachment member (11, 23, 111) to each other; a partition member (17, 117) which partitions a liquid chamber (14, 114) in the second attachment member (11, 23, 111) into a main liquid chamber (15, 115) having the elastic body (13, 113) as a portion of a partition wall and an auxiliary liquid chamber (16, 116); and a diaphragm (19, 119) which constitutes a portion of a partition wall of the auxiliary liquid chamber (16, 116), wherein one of both end opening portions of the second attachment member (11, 23, 111) in an axial direction is closed by the elastic body (13, 113) and the other thereof is closed by the diaphragm (19, 119), wherein a fixing portion (20b, 120b) which fixes the second attachment member (11, 23, 111) is formed on the metal bracket (20, 120), wherein a fixed portion (11g, 23c, 111c) which is fixed to the fixing portion of the metal bracket (20, 120) is formed on the second attachment member (11, 23, 111), wherein a gap (S2, S21) is provided between a portion of an outer circumferential surface of the second attachment member (11, 23, 111) except for the fixed portion (11g, 23c, 111c), and a portion of an inner circumferential surface of the metal bracket (20, 120) except for the fixing portion (20b, 120b), and wherein a second seal portion (22, 123) is provided between the fixed portion (11g, 23c, 111c) and the fixing portion (20b, 120b), characterized in that the gap (S2, S21) is a vacuum sealed space.