Abstract: Herein discloses is a testing device, comprising therein an inlet port introducing a blood specimen thereinto, a blood separating chamber held in fluid communication with the inlet port through a fluid passageway to receive a blood specimen, and a hemolyzed blood chamber having accommodated therein a hemolyzed blood fluid. The testing device is operative to be rotated around a rotation center and stop from being rotated to have the blood specimen accommodated in the blood separating chamber into blood cells and a blood plasma fluid, and the blood separating chamber is held in fluid communication with the passageway merging area through a fluid passageway to have the blood plasma fluid separated from the blood specimen flowed through the fluid passageway, in such a manner that the hemolyzed blood fluid is mixed and diluted with the blood plasma fluid in the passageway merging area at a predetermined dilution ratio.