PROBLEM TO BE SOLVED: To reduce the thickness of a probe by improving the configuration of a light guiding member for irradiating a biological body with light emitted from the light emitting element, reducing the loss of the light incident on the biological body.SOLUTION: The probe adapted to measure biological signals includes: a light emitting element 1, configured to emit the light having at least one wavelength a light guiding member 5, comprising:a first end face, being light-reflective and having a first part opposing the light emitting element and a second part surrounding the first parta second end face, being light-reflective and intersecting the first end face and a third end face, being light-permeable, opposing the first end face and intersecting the second end face, the light guiding member configured such that the light is reflected by at least one of the first end face and the second end face, and emitted from the third end face as the irradiation light and a light receiving element 2, configured to receive light reflected by the measured portion. A cross-sectional shape of the first end face in a direction along an optical axis of the light emitting element is such a shape that at least the second part is coincident with a circumference of an ellipse intersecting a minor axis of the ellipse, and the optical axis of the light emitting element is coincident with the minor axis of the ellipse.COPYRIGHT: (C)2009,JPO&INPIT【課題】発光素子からの光を生体に照射する導光部材の構成を改善して、生体への入射光を減少させることなく、プローブの厚みを薄くする。【解決手段】生体信号測定用プローブであって、少なくとも1つの波長の光を出射可能な発光素子1と、導光部材5であって、発光素子と対向する第1部分と第1部分を包囲する第2部分を含む光反射性の第1端面と、第1端面と交差する光反射性の第2端面と、第2端面と交差すると共に第1端面と対向する光透過性の第3端面を有し、第1端面と第2端面の少なくとも一方で反射しつつ第3端面より照射光として出射させるものと、被測定部より反射した光を受光可能とされた受光素子2とを具備して成り、第1端面の発光素子の光軸に沿う向きの断面形状は、少なくとも第2部分が楕円の短軸と交差する周の一部と一致しており、発光素子の光軸と楕円の短軸とが一致するように構成されている。【選択図】図1
