To develop a compacting device of the integrated structure of a compression chamber, a press lid, a main cylinder, a gate, an operation unit, etc., with each other.

A pre-compression chamber to be formed at an end part of a throw-in box of a waste car, etc., an openable press lid 4 whose base part is pivotably fitted to a device body, a lid pressing cylinder 5 to open/close the pressing lid 4, a pressing box 6, a main cylinder 7 to operate the pressing box, a gate 8, a gate cylinder 9 to open/close the gate, an operation unit, etc., are integrated with each other. The compressive reaction on the pressing lid is reduced by providing the pre-compression chamber, and the compression process and the discharge process can be realized only by the main cylinder by controlling respective solenoid valves provided on the lid pressing cylinder, the main cylinder, and the gate cylinder.