IN-VEHICLE TEMPERATURE CONTROL SYSTEM

An in-vehicle temperature control system (1) includes: a heater core (43) used to heat an inside of a vehicle cabin using heat of a heat medium; a first heating unit (52) that heats the heat medium using exhaust heat of an internal combustion engine (110); a thermal circuit configured to circulate the heat medium between the heater core (43) and the first heating unit (52); a distribution state switching mechanism (44, 45) that switches a distribution state of the heat medium between a first distribution state and a second distribution state; and a control device (6) that controls the distribution state switching mechanism (44, 45), wherein: the thermal circuit includes a bypass flow path (4f) disposed in parallel with the heater core (43).