To provide a microchip capable of reducing heat conductivity to enhance the precision of a temperature in a temperature-regulated part.

The temperature-regulated part 15 temperature-regulated by a temperature controller 20 having a Peltzier element 21 is set in a flow passage part 14 installed in a chip main body 11 of the microchip 10. A groove 16 is provided in an outer circumferential side of the temperature-regulated part 15 to surround the temperature-regulated part 15 discontinuously excepting the flow passage part 14. The groove 16 penetrates the chip main body 11 through along a plate thickness direction. Heat conduction between the temperature-regulated part 15 and the outer circumferential side of the groove 16 is reduced by installing the groove 16 in a circumference of the temperature-regulated part 15. The temperature of the temperature-regulated part 15 is controlled precisely by this manner.