To provide dehumidifying structure for a gas charging device capable of charging gas of high quality with high dehumidifying ability always maintained by efficiently applying heating treatment for the regeneration of a gas dehumidifying device provided at the gas charging device.

In this dehumidifying structure for a gas charging device constituted to compress gas from a gas supply source by a compressor driven by an engine, a dehumidifying device 46 is provided at an intermediate part of a gas supply path 27, and a heating pipe 63 for heating the dehumidifying device 46 is connected to the dehumidifying device 46. In this structure, exhaust gas from the engine is led into the heating pipe 63.