A blood sample collecting device (10) includes a vacuum blood sampling chamber (13) having a blood container (1) disposed therein, and a vacuum pump (17) for evacuating the vacuum blood sampling chamber to collect a blood sample into the blood container under a vacuum developed in the vacuum blood sampling chamber. The amount of collected blood in the blood container, and the vacuum in the vacuum blood sampling chamber is lowered below a preset pressure on the condition that a rate of increase in the measured amount of collected blood does not reach a predetermined normal rate of increase.
