An air handling unit comprising an air suction module, a mixing module, a heat exchange module and an air discharge module arranged in sequence in a flow direction of conditioning air so as to form flow paths of the conditioning air for an air conditioning cycle on a per function basis, wherein each of the air suction module, the mixing module, the heat exchange module and the air discharge module includes: a base to support the weight of the module; a plurality of module frames that are installed on the base and that form a framework of the respective module (100, 200, 300, 400); a plurality of case panels coupled to the plurality of module frames to form surfaces of the respective module (100, 200, 300, 400) while shielding an inner space of the respective module (100, 200, 300, 400) from an external space except for the flow paths of the conditioning air, wherein the plurality of module frames include a plurality of edge frames that form edges of the respective module (100, 200, 300, 400); and at least one connecting clamp configured to couple to each other one edge frame of a first module of at least two modules (100, 200), and one edge frame of a second module disposed next to the edge frame of the first module, wherein the at least one connecting clamp includes: a first module connection end portion having one end secured to the edge frame of the first module and the other end provided with male threads; a second module connection end portion having one end secured to the edge frame of the second module and the other end provided with male threads (62a"); and an adjusting nut located between the other end of the first module connection end portion and the other end of the second module connection end portion, the adjusting nut having axial connection holes formed in one side and the other side thereof for insertion of the other end of the first module connection end portion and the other end of the second module connection end portion. a base to support the weight of the module; a plurality of module frames that are installed on the base and that form a framework of the respective module (100, 200, 300, 400); a plurality of case panels coupled to the plurality of module frames to form surfaces of the respective module (100, 200, 300, 400) while shielding an inner space of the respective module (100, 200, 300, 400) from an external space except for the flow paths of the conditioning air, wherein the plurality of module frames include a plurality of edge frames that form edges of the respective module (100, 200, 300, 400); and at least one connecting clamp configured to couple to each other one edge frame of a first module of at least two modules (100, 200), and one edge frame of a second module disposed next to the edge frame of the first module, wherein the at least one connecting clamp includes: a first module connection end portion having one end secured to the edge frame of the first module and the other end provided with male threads; a second module connection end portion having one end secured to the edge frame of the second module and the other end provided with male threads (62a"); and an adjusting nut located between the other end of the first module connection end portion and the other end of the second module connection end portion, the adjusting nut having axial connection holes formed in one side and the other side thereof for insertion of the other end of the first module connection end portion and the other end of the second module connection end portion. a first module connection end portion having one end secured to the edge frame of the first module and the other end provided with male threads; a second module connection end portion having one end secured to the edge frame of the second module and the other end provided with male threads (62a"); and an adjusting nut located between the other end of the first module connection end portion and the other end of the second module connection end portion, the adjusting nut having axial connection holes formed in one side and the other side thereof for insertion of the other end of the first module connection end portion and the other end of the second module connection end portion.