An object of the present invention is to provide a microchip whereby, when chemical analysis is conducted, a specimen liquid can be directly collected and weighed without using any collecting and weighing devices. The present invention provides a microchip for analyzing liquid samples, which has a measuring structure for weighing and collecting a given amount of a specimen liquid within a range of 0.05 to 10 μl from an excessive amount of the specimen liquid which was introduced in the chip, wherein the measuring structure is located at the upstream side of an analysis element for analyzing a target substance in the specimen liquid inside the microchip.