The present invention is a biosensor (1) for electrochemically measuring a sample, which enables easy control of the timing at which a collected sample is transitioned to the testing site; characterized in the provision of: a circuit board (2) made of an insulating material;
an electrode system (3) including a working electrode (3B) and a counter electrode (3A) formed on the circuit board (2);
a cover member (4) fixed over the circuit board (2) so as to cover at least a part of the electrode system (3);
a sample flow channel (8) provided between the circuit board (2) and the cover member (4) to allow communication between the outside and a part of the electrode system (3) covered by the cover member (4);
a hydrophilic section provided on at least a part of the internal surface of the sample flow channel (8) and extending from a first end (8A) near the electrode system (3) side to the second end on the opposite side; and
a hydrophobic section (12) provided on a section adjacent to the second end on the circuit board (2) or on the internal surface of the sample flow channel (8) to temporarily stop the flow of the sample into the electrode system (3).
