A brain wave detection electrode (50) includes a pillar-shaped basal part (51) (base part), a plurality of polygonal pyramid-shaped protrusions (60) (protruding parts) that are elastic bodies and provided perpendicularly to one end face (a protrusion formation surface (52)) of the basal part (51), and electrode parts (80) provided on tip portions of the protrusions (60), in which H/D, which is a ratio As of a width D of a bottom surface of the polygonal pyramid shapes to a height H of the polygonal pyramid shapes, is equal to or more than 1.2 and equal to or less than 2.0.