To enhance heat transfer efficiency of a plate type evaporator being used in an absorption hot and chilled water generator by setting the distance between respective plates at a relatively small value and entraining a liquid phase refrigerant film being introduced by vapor flow to adhere to the plate in the lateral direction thereby thinning the liquid phase refrigerant film.

A plate type evaporator comprises a plurality of plates 1 having an internal cooling water passage 1a arranged at an interval δ and a liquid film is formed along the heat transfer surface 1b by dripping refrigerant R from an upper dripping pipe 2. Cooling water in the cooling water passage 1a is cooled by evaporating the liquid film. Reynolds number Ref of refrigerant film, i.e., dripping rate of refrigerant, is set correctly by limiting the interval 5 of the plate and making an opening in the left/right direction. Evaporated refrigerant R produces a transverse flow S and when the interval δ is limited appropriately, liquid-phase refrigerant R is entrained in the left/right direction by the vapor flow S. Consequently, the liquid-phase refrigerant film is made thin and evaporation thereof is accelerated.