An air-conditioning apparatus including an outdoor unit having a compressor, an expansion valve, a heat-source-side heat exchanger, and an outdoor air blower configured to blow air to the heat-source-side heat exchanger, and an indoor unit having a user-side heat exchanger and an indoor air blower configured to blow air to the user-side heat exchanger, comprising: a measuring unit configured to acquire operating-state data of the air-conditioning apparatus; a controller configured to control at least one of the operating capacity of the compressor, the air volume of the outdoor air blower, the air volume of the indoor air blower, and the opening of the expansion valve on the basis of the operating-state data; and a storage for storing the operating-state data, wherein the measuring unit acquires the outside air temperature flowing into the outdoor unit, the operating capacity of the compressor, and the operation mode as the operating-state data, the controller determines a current season in the site of installation of the air-conditioning apparatus and the elapse of the season cycle on the basis of at least the temperature of the outside air flowing into the outdoor unit, the operating capacity of the compressor, and the operating mode of the air-conditioning apparatus, stores information about the current operating-state data in the storage together with the number of the corresponding cycle and the information for identifying the season when it is found that the information about the operating-state data in the corresponding season in the corresponding cycle is not stored in the storage, and compares the operating-state data in the past season corresponding to the current season stored in the storage with current operating-state data and detects an abnormal state or a symptom of abnormality of the air-conditioning apparatus. a measuring unit configured to acquire operating-state data of the air-conditioning apparatus; a controller configured to control at least one of the operating capacity of the compressor, the air volume of the outdoor air blower, the air volume of the indoor air blower, and the opening of the expansion valve on the basis of the operating-state data; and a storage for storing the operating-state data, the measuring unit acquires the outside air temperature flowing into the outdoor unit, the operating capacity of the compressor, and the operation mode as the operating-state data, the controller determines a current season in the site of installation of the air-conditioning apparatus and the elapse of the season cycle on the basis of at least the temperature of the outside air flowing into the outdoor unit, the operating capacity of the compressor, and the operating mode of the air-conditioning apparatus, stores information about the current operating-state data in the storage together with the number of the corresponding cycle and the information for identifying the season when it is found that the information about the operating-state data in the corresponding season in the corresponding cycle is not stored in the storage, and compares the operating-state data in the past season corresponding to the current season stored in the storage with current operating-state data and detects an abnormal state or a symptom of abnormality of the air-conditioning apparatus.