An analyzing article comprising a fluid entrance port, and a plurality of capillary passages for moving a mobile component introduced from the fluid entrance port, wherein each capillary passage has a branching region that branches into a respective branch passage, each branch passage communicating with outside at a location other than the fluid entrance port for preventing the mobile component from moving beyond the branching region of the corresponding capillary passage, wherein the analyzing article further comprises a common passage communicating with each capillary passage at a location downstream of the corresponding branching region with respect to a flow direction of the mobile component, and at least one gas releasing port, other than the fluid entrance port, communicating with the common passage for releasing gas from within the capillary passages via the common passage to allow the mobile component to move in each capillary passage beyond the branching region, wherein each capillary passage includes at least one reagent region containing a reagent for reaction with a sample, and wherein the reagent region is located downstream from the branching region and upstream from the common passage in each capillary passage with respect to a flow direction of the mobile component, and the distance between the reagent region and the branching region being smaller than the distance between the branching region and the fluid entrance port, characterized in that the at least one gas releasing port has an openable closer which, when closed, prevents the mobile component from moving beyond the branching region and which, when open, releases gas from the common passage thereby allowing the mobile component to move in each capillary passage beyond the branching region into the reagent region. wherein each capillary passage has a branching region that branches into a respective branch passage, each branch passage communicating with outside at a location other than the fluid entrance port for preventing the mobile component from moving beyond the branching region of the corresponding capillary passage, wherein the analyzing article further comprises a common passage communicating with each capillary passage at a location downstream of the corresponding branching region with respect to a flow direction of the mobile component, and at least one gas releasing port, other than the fluid entrance port, communicating with the common passage for releasing gas from within the capillary passages via the common passage to allow the mobile component to move in each capillary passage beyond the branching region, wherein each capillary passage includes at least one reagent region containing a reagent for reaction with a sample, and wherein the reagent region is located downstream from the branching region and upstream from the common passage in each capillary passage with respect to a flow direction of the mobile component, and the distance between the reagent region and the branching region being smaller than the distance between the branching region and the fluid entrance port, characterized in that the at least one gas releasing port has an openable closer which, when closed, prevents the mobile component from moving beyond the branching region and which, when open, releases gas from the common passage thereby allowing the mobile component to move in each capillary passage beyond the branching region into the reagent region.