PROBLEM TO BE SOLVED: To provide a method and an apparatus in which temperature gradients are formed, both in the length direction and in the thickness direction of a passage installed in a microfluid device. ; SOLUTION: The temperature control apparatus for a microfluid device comprises (1) a first temperature control unit comprising a heating and cooling mechanism, capable of maintaining an almost uniform temperature of a surface D; and (2) a second temperature control unit, comprising a surface E in contact with a particular surface C of a microfluid device and a temperature control passage B at a position almost parallel to the surface E in which the temperature control fluid flows; and (3) a structure i, in which the microfluid device is held between the first temperature control unit and the second temperature control unit so that the surface D is in contact with the back of the surface D and also the surface C is in a state of contacting the surface E, or a structure ii in which the first temperature control unit, the second temperature control unit and the microfluid device are laminated, in this order, so that the surface D is in contact with the back of the surface E and also the surface E is in contact with the surface C. ; COPYRIGHT: (C)2008,JPO&INPIT