The brain electrode device S is a brain electrode device S having an electrode that can be inserted into the brain, and includes an elongated probe 100, an electrode portion 102 formed on the probe 100, an electrode portion 102 of the flexible probe 100 And an insertion member 3 detachably inserted into a first hole 103 formed in a flat surface. The probe 100 has a first region 104 on the side of the electrode portion 102 with respect to the position where the first hole 103 is formed and a second region 104 on the side of the electrode portion 102 with respect to the position where the first hole 103 is formed And the second region 105 on the opposite side. In the state where the probe 100 is folded at the position of the first hole 103 so that the second region 105 overlaps with the first region 104, the insertion member 3 has the 1 hole 103. As shown in FIG.脳電極装置Ｓは、脳内部に挿入可能な電極を有する脳電極装置Ｓであって、長尺状のプローブ１００と、プローブ１００に形成された電極部１０２と、可撓性を有するプローブ１００の平面に形成された第１の穴１０３に着脱可能に挿入された挿入部材３と、を有する。また、プローブ１００は、第１の穴１０３が形成された位置に対して電極部１０２の側の第１領域１０４と、第１の穴１０３が形成された位置に対して電極部１０２の側と反対側の第２領域１０５と、を有し、挿入部材３は、第２領域１０５が第１領域１０４と重なるように、プローブ１００が第１の穴１０３の位置で折り曲げられた状態で、第１の穴１０３に挿入されている。
