In an adsorber for an adsorption type refrigerator of the present invention, aluminum heat exchangers 120, 130 arranged in a casing 110 are provided with films which do not permit moisture to pass therethrough, such as SiO₃ films, anodic oxide coating films and several ppm to a hundred and several tens of ppm of inorganic negative ions such as PO₄^3-, SiO₃^2- are added in the water enclosed in the casing.