An operating method for a clothes treating apparatus comprising: a drum configured to accommodate therein an object to be dried; an air suction duct configured to form a flow path of air introduced into the drum; an auxiliary fan configured to introduce air into the air suction duct; an air exhaustion duct configured to form a flow path of air exhausted from the drum; a main fan configured to exhaust air to the air exhaustion duct from the drum; a condenser disposed to heat air sucked into the drum through the air suction duct; an evaporator disposed to cool air exhausted from the drum through the air exhaustion duct; and a compressor and an expander configured to constitute a heat pump together with the condenser and the evaporator, characterized in that the method comprising: measuring a discharge side pressure (Pd) of the compressor; and comparing the measured discharge side pressure (Pd) with a maximum allowable pressure (Pm), and determining that the auxiliary fan does not operate when the discharge side pressure (Pd) is more than the maximum allowable pressure (Pm), wherein the maximum allowable pressure (Pm) is determined by a peripheral temperature (Ta) of the condenser, wherein the maximum allowable pressure (Pm) is defined as a maximum pressure of a refrigerant when peripheral air of the condenser is normally supplied into the condenser in a steady state of the auxiliary fan. a drum configured to accommodate therein an object to be dried; an air suction duct configured to form a flow path of air introduced into the drum; an auxiliary fan configured to introduce air into the air suction duct; an air exhaustion duct configured to form a flow path of air exhausted from the drum; a main fan configured to exhaust air to the air exhaustion duct from the drum; a condenser disposed to heat air sucked into the drum through the air suction duct; an evaporator disposed to cool air exhausted from the drum through the air exhaustion duct; and a compressor and an expander configured to constitute a heat pump together with the condenser and the evaporator, characterized in that the method comprising: measuring a discharge side pressure (Pd) of the compressor; and comparing the measured discharge side pressure (Pd) with a maximum allowable pressure (Pm), and determining that the auxiliary fan does not operate when the discharge side pressure (Pd) is more than the maximum allowable pressure (Pm), wherein the maximum allowable pressure (Pm) is determined by a peripheral temperature (Ta) of the condenser, wherein the maximum allowable pressure (Pm) is defined as a maximum pressure of a refrigerant when peripheral air of the condenser is normally supplied into the condenser in a steady state of the auxiliary fan. measuring a discharge side pressure (Pd) of the compressor; and comparing the measured discharge side pressure (Pd) with a maximum allowable pressure (Pm), and determining that the auxiliary fan does not operate when the discharge side pressure (Pd) is more than the maximum allowable pressure (Pm), wherein the maximum allowable pressure (Pm) is determined by a peripheral temperature (Ta) of the condenser, wherein the maximum allowable pressure (Pm) is defined as a maximum pressure of a refrigerant when peripheral air of the condenser is normally supplied into the condenser in a steady state of the auxiliary fan.