A degassing apparatus 1 includes a housing 2 having a degassing chamber 22, a rotor 3 rotatably provided in the housing 2 and a decompressing mechanism 4 for decompressing the degassing chamber 22 of the housing 2. The housing 2 further includes a conduit line 21 and a cylindrical portion 23. The degassing chamber 22 is provided in a middle part of the conduit line 21. An upper end of the conduit line 21 constitutes an inlet port 24 and a lower end of the conduit line 21 constitutes an outlet port 25. The rotor 3 is rotatably provided inside the cylindrical portion 23 so that a passage between the outlet portion 25 and the degassing chamber 22 can be hermetically separated by the rotor 3. The rotor 3 has four partitioning plates 31 which partition the inside of the cylindrical portion into four spaces 231-234.