PROBLEM TO BE SOLVED: To provide a resin microchip having a microchannel having a transparent flow passage of low absorption in an ultraviolet area sealed with a fine upper substrate of excellent surface smoothness and high dimensional precision. ;SOLUTION: This microchip for conducting electric and/or optical measurement for a liquid sample has at least a lower substrate having a micro flow passage through which the liquid sample flows, and the upper substrate. In the microchip, at least the lower substrate comprises a transparent hydrocarbon polymer expressed by formula (1), and a relative element concentration of oxygen by X-ray photoelectron spectrometry (XPS) analysis is 5at% or more at least on the surface on the side having the flow passage of the lower substrate.