To provide a device for decontaminating tritium which safely decontaminates materials to be treated made of metal and non-metal contaminated with tritium in a short time and a method for decontaminating them.

The device for decontaminating tritium which decontaminates the materials to be treated contaminated with tritium in a gas atmosphere to recover the tritium is characterized in that the device has a heating container which accommodates the material to be treated and can encapsulate and seal a gas, a high-frequency induction heating component which conducts high-frequency induction heating for the materials to be treated, a microwave heating component which carries out microwave heating for the materials to be treated, a tritium recovery component which circulates the gas in the heating container and recovers the tritium emitted into the heating container from the material to be treated and a controller which controls the switchover between the high-frequency induction heating component and the microwave heating component and heating temperatures.