Conventional liquid transport substrates having a fluid channel formed along an array of electrodes have a problem in which throughput decreases, depending on driving conditions. In order to avoid two-way passage in a fluid channel from the inlet to a measuring section and a fluid channel from the measuring section to the outlet, the measuring section is located in the middle of the fluid channel connecting the inlet and the outlet, so that manipulation from the inlet to the outlet takes place in one direction on the substrate. Even when analyzing a large number of sample droplets, by transport of the droplets substantially in one direction, it is possible to complete measurement in a short time.