An adsorption refrigerator includes a vacuum vessel within which a required amount of refrigerant is hermetically filled, and there are housed a first finned tube for routing therethrough a heating medium on the heat source side, which tube has an adsorbent packed and held in fin interstices, and a second finned tube for routing therethrough a heating medium on the utilization side, which tube serves as a vaporizer and condenser. The refrigerator further may be provided, at the bottom portion of the vessel, with refrigerant heating means for heating and vaporizing the refrigerant during desorption. Otherwise, where the amount of refrigerant is adjusted, the refrigerator may be provided with refrigerant heating and cooling means for heating to vaporize the refrigerant during desorption and for cooling to condense refrigerant vapors, at the bottom portion of the vessel, and with a refrigerant reservoir for reception of the adjusted amount of refrigerant, which reservoir is connected through a line and valve to the bottom of the vessel, below the bottom of the vessel. The first finned tube preferably has a fin pitch of 1 to 10 mm and a fin height of 5 to 20 mm. With the refrigerator, even low-temperature fluid of less than 80.degree. C. may be utilized for the heat source-side heating medium.