A cooling system (1) includes: a compressor (12) that circulates refrigerant; a heat exchanger (14) and a heat exchanger (15) that carry out heat exchange between refrigerant and outside air; a decompressor (16) that decompresses refrigerant; a heat exchanger (18) that carries out heat exchange between refrigerant and air-conditioning air; a cooling portion (30) that is provided in a path of refrigerant flowing between the heat exchanger (14) and the heat exchanger (15) and that uses refrigerant to cool a heat generating source (31); a first line (24) through which refrigerant circulates between the cooling portion (30) and the heat exchanger (15); a second line (27) through which refrigerant circulates between the heat exchanger (18) and the compressor (12); and an internal heat exchanger (40) in which refrigerant that circulates through the first line (24) and refrigerant that circulates through the second line (27) exchange heat with each other.