PROBLEM TO BE SOLVED: To provide a brain wave measuring electrode surely coming come into contact with a scalp through a space between hairs to secure conduction without applying excessive pressure to the scalp, and to provide a cap with the brain wave measuring electrode and a brain wave measuring device.SOLUTION: A brain wave measuring electrode includes: a chip part abutted on a measuring object to receive an electric signal from the measuring object and a signal transmitting part for receiving the electric signal from the chip part and transmitting the same to a signal processor. A surface of the chip part that abuts on the measuring object is provided with a projection having conductivity, flexibility and elasticity. In addition, the projection is formed of metal material with conductivity and the projection has a stretching property by being energized by an elastic member in the vertical direction to a contact surface with the measuring object.COPYRIGHT: (C)2013,JPO&INPIT【課題】頭皮に対して過度の圧力を加えることなく、頭髪の間を通して頭皮に確実に接触し導通を確保できる脳波測定用電極、脳波測定用電極付きキャップ及び脳波測定装置を提供する。【解決手段】脳波測定用電極は、測定対象に当接して測定対象から電気信号を受け取るチップ部と、チップ部から電気信号を受け取り信号処理装置へ伝達する信号伝達部と、を備える。チップ部の測定対象と当接する面には導電性と、可撓性又は伸縮性と、を有する突起が形成され、突起は導電性を有する金属材料で形成されており、突起は弾性部材によって測定対象との接触面に対して垂直方向に付勢されることにより伸縮性を有する。【選択図】図16A