The ITER Central Solenoid (CS) model coil and the CS insert coil were fabricated, and the test was carried out. The AC loss measurement of the coils is one of the most important tests to determine coil performance. The AC loss of a short sample conductor for the CS insert coil was measured by using the calorimetric method, and the coupling time constants of the conductor were estimated to be 30ms and 20ms for pulse and discharge tests, respectively. The AC loss of the CS insert coil was measured by using the calorimetric method for pulse and discharge tests. The coupling time constant estimated from the result of the pulse tests was 34ms and almost equal to that of the short sample. The coupling time constant for the discharge test was estimated to be 140ms and about 4 times that of the pulse test.