A micro-channel device provided in a solution analysis system using pressure liquid feed comprises a plurality of straight-line channels and curved channels connecting the ends of the neighboring straight-line channels. The width w of each curved channel is smaller than the width t of each straight-line channel. The radius of curvature r of each curved channel is set so that the value of a expressed by formula (1) is equal to or smaller than the value of a at a local maximum point of the theoretical step height H expressed by formula (2) and based on the shape of the curved channel. a=w/r  (1) H = u c  w 2 64  γ   D m × a 2  ( a + 2 ) a + 1 ( 2 ) Where, w is a width of the curved channel, uc is a channel passing speed of a solution in the curved channel, γ is a molecular diffusion inhibition factor by basic members present in the curved channel, and Dm is a molecular diffusion coefficient of the solution.