A method of controlling an air conditioner, comprising: activating (S11, S12; S31, S32), by a controller, a refrigeration cycle by driving a compressor; detecting, by a pressure sensor (175, 170), a high pressure and a low pressure of the refrigeration cycle when the refrigeration cycle is activated; adjusting, by the controller, an operating frequency of the compressor based on the detected high pressure or the detected low pressure of the refrigeration cycle; determining (S13; S33), by a load detecting unit, a current load of an inside space, a load level of the inside space being determined by comparing (SI4, S15; S34, S35, S38) the current load with a reference load; and determining (S17, S19; S37, S40, S42), by the load detecting unit, the operating frequency of the compressor based on the determined load level, wherein the load detecting unit comprises: a frequency detector to detect the operating frequency of the compressor, and a power detector to detect current consumption and power consumption occurring upon the activation of the refrigeration cycle, wherein the load level comprises: a high load in which the current load is greater than or equal to the reference load; and a low load in which the current load is less than the reference load, wherein the reference load is a load corresponding to when an increase rate of the operating frequency of the compressor is a first set increase rate, or a load corresponding to when an increase rate of the power consumption or current consumption is a second set increase rate, and wherein, when it is determined that the increase rate of the operating frequency of the compressor is greater than the first set increase rate or when the increase rate of the power consumption or current consumption is greater than the second set increase rate, the current load is determined as the high load. activating (S11, S12; S31, S32), by a controller, a refrigeration cycle by driving a compressor; detecting, by a pressure sensor (175, 170), a high pressure and a low pressure of the refrigeration cycle when the refrigeration cycle is activated; adjusting, by the controller, an operating frequency of the compressor based on the detected high pressure or the detected low pressure of the refrigeration cycle; determining (S13; S33), by a load detecting unit, a current load of an inside space, a load level of the inside space being determined by comparing (SI4, S15; S34, S35, S38) the current load with a reference load; and determining (S17, S19; S37, S40, S42), by the load detecting unit, the operating frequency of the compressor based on the determined load level, wherein the load detecting unit comprises: a frequency detector to detect the operating frequency of the compressor, and a power detector to detect current consumption and power consumption occurring upon the activation of the refrigeration cycle, wherein the load level comprises: a high load in which the current load is greater than or equal to the reference load; and a low load in which the current load is less than the reference load, wherein the reference load is a load corresponding to when an increase rate of the operating frequency of the compressor is a first set increase rate, or a load corresponding to when an increase rate of the power consumption or current consumption is a second set increase rate, and wherein, when it is determined that the increase rate of the operating frequency of the compressor is greater than the first set increase rate or when the increase rate of the power consumption or current consumption is greater than the second set increase rate, the current load is determined as the high load. a frequency detector to detect the operating frequency of the compressor, and a power detector to detect current consumption and power consumption occurring upon the activation of the refrigeration cycle, wherein the load level comprises: a high load in which the current load is greater than or equal to the reference load; and a low load in which the current load is less than the reference load, wherein the reference load is a load corresponding to when an increase rate of the operating frequency of the compressor is a first set increase rate, or a load corresponding to when an increase rate of the power consumption or current consumption is a second set increase rate, and wherein, when it is determined that the increase rate of the operating frequency of the compressor is greater than the first set increase rate or when the increase rate of the power consumption or current consumption is greater than the second set increase rate, the current load is determined as the high load. a high load in which the current load is greater than or equal to the reference load; and a low load in which the current load is less than the reference load, wherein the reference load is a load corresponding to when an increase rate of the operating frequency of the compressor is a first set increase rate, or a load corresponding to when an increase rate of the power consumption or current consumption is a second set increase rate, and wherein, when it is determined that the increase rate of the operating frequency of the compressor is greater than the first set increase rate or when the increase rate of the power consumption or current consumption is greater than the second set increase rate, the current load is determined as the high load.