Biological information acquisition device and biological information acquisition method

In the present invention, biological information can be favorably acquired even in a case where the characteristic amounts of biological data can fluctuate due to various factors. A biological information acquisition device (1) acquires biological information used for comparison. The biological information acquisition device (1) comprises a blood flow increase operation unit (2a), a biological information acquisition unit (2b), a characteristic amount evaluation unit (2c), and a reacquisition determination unit (2d). The blood flow increase operation unit (2a) increases the blood flow of a subject. The biological information acquisition unit (2b) acquires biological information of the subject. The characteristic amount evaluation unit (2c) evaluates the characteristic amount of the acquired biological information. In a case where the evaluated characteristic amount does not meet a predetermined threshold value, the reacquisition determination unit (2d) causes the blood flow increase operation unit (2a) to ope