An apparatus 1 for disposal of wastes comprises a measuring hopper 2 for measuring a charging amount of a waste to be disposed such as domestic wastes, industrial wastes or the like or a charging amount of a solid fuel such as coke, coal or the like, a charging hopper 3 for charging the waste and the solid fuel respectively measured with the measuring hopper 2, a melting furnace 4 for melting the waste charged from the charging hopper 3 at a high temperature to conduct detoxification thereof, and a charging damper 5 arranged between the charging hopper 3 and the melting furnace 4 and having a multistage sluice valve system 9 capable of charging the waste and the solid fuel charged in the charging hopper 3 into the melting furnace 4 without outflowing of a furnace gas to exterior.