In order to compensate power fluctuations caused by loads and renewable energy sources, the concept of controllable load has been proposed. In this paper, the use of heat pump air conditioning system as a controllable load is focused. To analyze the feasibility of using the heat pump for power fluctuation compensation, basic characteristics of heat pump concerning its power consumption and processed heat are measured by experiments and reported in this paper. The COP characteristics show that the efficiency of the heat pump is not affected so much by power consumption as long as it is operated above a certain level of power consumption. The Bode diagram of sinusoidal reference signal test shows that the heat pump can compensate power fluctuation which is in a certain region in the frequency domain without giving a large effect on processed heat.