To prevent leakage of harmful matter such as dioxins to the outside by preventing simultaneous opening of an outer input opening and an inner input opening by mechanical control and not by electrical control in an incinerator adopting an input structure for objects to be burned having the outer input opening and the inner input opening.

The incinerator 1 has the outer input opening 400 and the inner input opening 300, and it is provided with an input part 2 for the objects to be burned communicating the inner input opening 300 with an incineration chamber 1 and temporarily holding the objects to be burned for inputting them in the incineration chamber 1, an outer door 4 opening and closing the outer input opening 400, a vertically moving type inner door 3 opening and closing the inner input opening 300, and a latch member 51 latching the outer door 4 to prevent it from opening. The latch member 51 is composed so that by lifting the inner door 3 and opening the inner input opening 300, a forward side moves to latch the outer door 4 so it does not open, and by lowering the inner door 3 and closing the inner input opening 300, the forward side moves to release latching of the door 4 so that it can be opened.