Problem to be solved: to provide a measuring method using a biosensor and a biosensor capable of stably detecting and measuring weak biological signals.The biosensor 100A has at least one of flexible and stretchable and has a band like base material 1 capable of winding over a whole circumference of a predetermined position of the organism, and at least one detection electrode 2 provided on the main surface of the body side of the base substrate 1 to detect the biological signal of the organism, and the base Provided that at least one ground electrode 3 located at a different position from the detecting electrode 2 on the main surface of the body 1 of the sheath substrate 1 is provided, and the base substrate 1 is wound over the whole circumference of the predetermined position of the organism when groundGround electrode 3 is provided on base substrate 1 so that electrode 3 covers detection electrode 2.Selection diagram【課題】着心地がよく、かつ、微弱な生体信号を安定的に検出することができる生体センサおよび生体センサを用いた測定方法を提供する。【解決手段】生体センサ100aは、可撓性および伸縮性の少なくとも一方を有し、生体の所定部位の全周以上に巻付け可能な帯状のベース基材1と、ベース基材1の生体側の主面上に設けられ、生体の生体信号を検出する少なくとも1つの検出電極2と、ベース基材1の生体側の主面上の検出電極2とは異なる位置に設けられた少なくとも1つのグランド電極3と、を備え、ベース基材1を生体の所定部位の全周以上に巻付けたときにグランド電極3が検出電極2を覆うようにグランド電極3がベース基材1上に設けられている。【選択図】図1B
