To provide a heating/cooling system including a countermeasure to dew condensation by concealing and burying a radiator in a partitioning wall of a living room.

A heating/cooling circulation type all plastic resin radiator He is suspended and supported in a space O closed at its upper and lower parts by corbels 6K in a wall partition WA, a drain means is disposed below the radiator, a front face of the radiator He in the space O includes a front interior material 8A having superior thermal radiation wave absorbing/radiating properties, and louvers 7A for transmission of air in the space O are disposed at upper and lower parts of the front interior material 8A.