an evaporator configured to perform heat exchange;

a defrost heater configured to operate to remove frost from the evaporator;

a temperature sensor configured to detect an ambient temperature of the evaporator; and

a controller configured to control the defrost heater,

wherein, in response to a defrosting operation start time point arriving, the controller is configured to perform a defrost operation mode including a pre-defrost cooling mode, a heater operation mode, and post-defrost cooling mode, perform a pulse operation mode in which the defrost heater is repeatedly turned on and off based on the heater operation mode, and change a magnitude of cooling power supplied in the post-defrost cooling mode based on an ON period of the defrost heater or a temperature of a cooling compartment in the pulse operation mode,

wherein the pre-defrost cooling mode includes:

a first period in which cooling power of a first level is supplied,

a second period in which cooling power of a second level higher than the first level is supplied,

a third period in which cooling power is not supplied,

a fourth period in which cooling power of the first level is supplied,

wherein the fourth period is shorter than the first period, and the heater operation mode is performed after the fourth period,

wherein the magnitude of the cooling power supplied in the post-defrost cooling mode is greater than the second level in the pre-defrost cooling mode.