To provide a glass tube heater for defrosting to be safely used even if integrated into a refrigerator using a flammable refrigerant.

The glass tube heater for defrosting in a refrigerator has a refrigerant circuit which connects a compressor, a condenser, a decompressing device, and an evaporator annularly with a refrigerant tube and which is filled with a flammable refrigerant. The glass tube heater is integrated into the refrigerator in which the evaporator is used for cooling a storage compartment formed as a heat insulating box, and is disposed near the evaporator to thaw the frost formed on the evaporator. Since the glass tube heater is surrounded by wire gauze with at least 30 meshes, if the flammable refrigerant leaks and touches the glass tube heater, burning occurs between the wire gauze and the surface of the glass tube heater and the flame is hardly propagated to the outside of the wire gauze, so that the fire will hardly spread to the refrigerator.