A garment dryer comprising: a treatment tub in which a garment to be dried is retained; an air circulation duct having opposite ends connected to the treatment tub for causing air to flow out of the treatment tub through one of the opposite ends and flow back into the treatment tub through the other end; air blowing means for circulating the air through the air circulation duct; and a heat pump device including a heat absorber, a compressor, a radiator and pressure reducing means which are connected by a coolant pipe through which a coolant flows, the heat absorber being adapted to cool the air flowing through the air circulation duct to dehumidify the air, the radiator being adapted to heat the dehumidified air; the heat absorber and the radiator each having an airflow plane for heat exchange with the air, and the airflow plane of the heat absorber and the airflow plane of the radiator being disposed in this order with respect to an airflow direction in opposed relation in the air circulation duct; the air circulation duct including an upstream buffer space provided upstream of the airflow plane of the heat absorber with respect to the airflow direction for changing a flow direction of the air to regulate a flow rate of the air; characterized in that the heat pump device further includes a casing having a generally rectangular box shape, wherein a heat exchange air duct portion through which the air flows is defined in the casing, wherein the heat absorber and the radiator are provided in the air duct portion, in that a sub-casing is attached to an upper surface of the casing and has a wedge-like plan shape, wherein the air taken out of the treatment tub flows into the sub-casing from an inlet port of the sub-casing 21, wherein the sub-casing is provided in an air inlet passage to the casing, wherein an upper surface portion of the casing is opposed to a lower portion of an inlet port of the sub-casing to define a buffer space in which the air is deflected from a downward direction to a lateral direction around the sub-casing by the upper surface portion. a treatment tub in which a garment to be dried is retained; an air circulation duct having opposite ends connected to the treatment tub for causing air to flow out of the treatment tub through one of the opposite ends and flow back into the treatment tub through the other end; air blowing means for circulating the air through the air circulation duct; and a heat pump device including a heat absorber, a compressor, a radiator and pressure reducing means which are connected by a coolant pipe through which a coolant flows, the heat absorber being adapted to cool the air flowing through the air circulation duct to dehumidify the air, the radiator being adapted to heat the dehumidified air; the heat absorber and the radiator each having an airflow plane for heat exchange with the air, and the airflow plane of the heat absorber and the airflow plane of the radiator being disposed in this order with respect to an airflow direction in opposed relation in the air circulation duct; the air circulation duct including an upstream buffer space provided upstream of the airflow plane of the heat absorber with respect to the airflow direction for changing a flow direction of the air to regulate a flow rate of the air; characterized in that the heat pump device further includes a casing having a generally rectangular box shape, wherein a heat exchange air duct portion through which the air flows is defined in the casing, wherein the heat absorber and the radiator are provided in the air duct portion, in that a sub-casing is attached to an upper surface of the casing and has a wedge-like plan shape, wherein the air taken out of the treatment tub flows into the sub-casing from an inlet port of the sub-casing 21, wherein the sub-casing is provided in an air inlet passage to the casing, wherein an upper surface portion of the casing is opposed to a lower portion of an inlet port of the sub-casing to define a buffer space in which the air is deflected from a downward direction to a lateral direction around the sub-casing by the upper surface portion.