A vehicle thermal management system includes a switching portion that switches between a state in which a heat medium circulates through a heat-medium cooling heat exchanger and a state in which the heat medium circulates through a heat-medium heating heat exchanger with respect to each of an engine heat-transfer portion and a heat-generating device, a flow-rate adjustment portion that adjusts the flow rate of the heat medium for each of a heat-medium outside-air heat exchanger and the engine heat-transfer portion, an air-conditioning requesting portion that makes a cooling request for an air cooling heat exchanger to cool the ventilation air as well as a heating request for an air heating heat exchanger to heat the ventilation air, and a controller that controls an operation of at least one of the switching portion, a compressor, and the flow-rate adjustment portion based on presence/absence of the cooling request and presence/absence of the heating request from the air-conditioning requesting portion.