A laminate type evaporator in which a large number of refrigerant tubes including at least a pair of first and second refrigerant flow passages are laminated together, comprising: a refrigerant tube group in which a pair of first and second upper tank portions are respectively arranged at one end of the first and second refrigerant flow passages and in which a pair of first and second lower tank portions are respectively arranged at the other end of the first and second flow passages; a first partition portion arranged in the first lower tank portion of the refrigerant tube group; a second partition portion arranged in the second upper tank portion of the refrigerant tube group, a second side refrigerant passage is positioned at the other end of the refrigerant tube group with respect to the second partition portion and is configured to communicate the first upper tank portion and the second upper tank portion of the refrigerant tube with each other; a third side refrigerant passage is positioned at said other end with respect to the first partition portion and is configured to communicate the first lower tank portion and the second lower tank portion of the refrigerant tube with each other; and wherein the first partition portion and the second partition portion are arranged such that they divide the refrigerant tube group into three refrigerant flow passage groups (B11, B12, B13) sequentially circulating refrigerant introduced from the refrigerant inlet from the first lower tank portion of the refrigerant tube at said one end to the second upper tank portion of the refrigerant tube at said one end, characterized in that a second refrigerant flow passage group is constructed such that a refrigerant flow consisting of first (R12a) and second (R12b) refrigerant flows is formed, the first refrigerant flow passages contained in the second refrigerant flow passage group are adapted to provide the first refrigerant flow (R12a) from the first upper tank portion to the first lower tank portion, the second refrigerant flow passages contained in the second refrigerant flow passage group are adapted to provide the second refrigerant flow (R12b) from the second upper tank portion to the second lower tank portion, so that the evaporator is adapted to branch the refrigerant to flow from a rear half portion of the first upper tank portion in a rear half portion of the first lower tank portion as the first refrigerant flow and in the second side refrigerant passage as the second refrigerant flow, to flow the second refrigerant flow having flown in the second side refrigerant passage through a rear half portion of the second upper tank portion in a rear half portion of the second lower tank portion, to flow the first refrigerant flow having flown in the rear half portion of the first lower tank portion through the third side refrigerant passage in the rear half portion of the second lower tank portion, and to join the first and second refrigerant flows with each other at the rear half portion of the second lower tank portion. a refrigerant tube group in which a pair of first and second upper tank portions are respectively arranged at one end of the first and second refrigerant flow passages and in which a pair of first and second lower tank portions are respectively arranged at the other end of the first and second flow passages; a first partition portion arranged in the first lower tank portion of the refrigerant tube group; a second partition portion arranged in the second upper tank portion of the refrigerant tube group, a second side refrigerant passage is positioned at the other end of the refrigerant tube group with respect to the second partition portion and is configured to communicate the first upper tank portion and the second upper tank portion of the refrigerant tube with each other; a third side refrigerant passage is positioned at said other end with respect to the first partition portion and is configured to communicate the first lower tank portion and the second lower tank portion of the refrigerant tube with each other; and wherein the first partition portion and the second partition portion are arranged such that they divide the refrigerant tube group into three refrigerant flow passage groups (B11, B12, B13) sequentially circulating refrigerant introduced from the refrigerant inlet from the first lower tank portion of the refrigerant tube at said one end to the second upper tank portion of the refrigerant tube at said one end,