The sample temperature regulator is provided with a heating block (3) having a sample container holder (6) and a temperature-controllable heater (7) and with a cooling block (4) having a cooling mechanism (11). These two blocks are combined with each other through a connecting plate (15) made of a material having a thermal conductivity lower than those of these blocks. This constitution can reduce heat transfer between the heating block and the cooling block and allows them to have wide temperature regulating ranges, as well as increased heating capacity and cooling capacity, respectively. Further, this constitution makes the structure of the temperature regulator simple and compact, so that the regulator has increased durability and can be offered at a low price.