A fluid temperature control device, which has a high cooling capacity, wide controllable temperature range and an excellent temperature control accuracy. A transparent cylinder (3) is inserted in a cylindrical-shaped vessel (1), and a columnar-shaped heating lamp (5) is inserted in the transparent cylinder (3). A fluid desired to be temperature controlled is made to flow in a passage (25) between the vessel (1) and the transparent cylinder (3). Joined to an outer peripheral al surface of the vessel (1) is a thermoelectric conversion element (7) , to an outer surface of which is joined a cooling pipe (9). A cooling liquid is made to flow in the cooling pipe (9) . Fluid heating is effected by the heating lamp (5). Fluid cooling is effected by the cooling liquid and the thermoelectric conversion element (7) forcibly absorbs heat from the fluid and discharges heat to the cooling liquid to thereby cool the fluid rapidly and cool the fluid to a temperature lower than that of the cooling liquid. Further, the thermoelectric conversion element (7) is used to suppress cooling by the cooling liquid and control an amount of cooling with good accuracy and good responsiveness.