A biogenic substance detector with high reaction efficiency and detection sensitivity is obtained.The biogenic substance detector includes: a plurality of chambers 1011 for hybridizing a target and a probe; and a passage 1012 provided between the chambers 1011. The cross-sectional area of the passage 1012 taken perpendicularly to the chamber-passage alignment direction is smaller than the cross-sectional area of each chamber 1011 taken perpendicularly to the chamber-passage alignment direction, and a probe-fixing area 1013 is provided over the entire inside wall of each chamber 1011. One kind of probe is fixed in one chamber 1011. In the hybridization step, the sample solution is made to move back and forth within the chambers 1011 and the passage 1012 using a pump 102.