To provide a microchip capable of varying the elapsed time (reaction time) after the mixing of two liquids until the measurement and being used for a reaction kinetics study.

The microchip comprises a base part and a moving part which are contacted each other through a sliding surface, wherein the position of the intersection is positioned according to the point where an opening disposed in the slidable moving part and a groove, disposed in the base part and with a major axis in the sliding direction of the moving part, are intersected, when different reagents are introduced into the passages, perforated in both the base and moving parts and intersected in the downstream, are mixed and reacted at the downstream intersection.