The present invention relates to control of activation of an air conditioning device. More particularly, the present invention provides a method for predicting the time of arrival of a preset indoor temperature based on information regarding environment factors, including a ventilation factor, and controlling the activation time of the air conditioning device such that the present temperature is reached at the target point of time according to the predicted time. In addition, the method provides a method for predicting the target point of time in view of the point of time at which the user will need the air conditioning device. In addition, the present invention provides a method for controlling activation of an air conditioning device in view of the optimal partial load factor of the air conditioning device until the presetting temperature is reached. The present disclosure relates to technologies for sensor networks, machine-to-machine (M2M) communication, machine type communication (MTC), and the Internet of things (IoT). The present disclosure may be utilized for intelligent services (smart homes, smart buildings, smart cities, smart cars or connected cars, health care, digital education, retail businesses, services related to security and safety, etc.).