A fluid temperature control device, which includes: a main body block having a passage channel formed in a surface thereof; a thermal conducting plate that is provided on the surface of the main body block, and covers the passage channel to form a passage for passing a fluid to be temperature controlled; and temperature control means that carries out heat exchanging (heating/cooling), by way of the thermal conducting plate, with the fluid passing through the passage, in which the passage abutting on the thermal conducting plate connects a fluid inlet and a fluid outlet formed in the main body block, and is a single passage having an approximately constant passage cross-sectional area over its entire length.