Abstract: A capacitance sensor includes: a board; a first electrode provided on the board; a flexible member fixed to the board; and a second electrode provided in the flexible member to face the first electrode with a gap between the second electrode and the first electrode and configured to detect a capacitance with the first electrode. The flexible member includes: an electrode inclusion portion including the second electrode in the electrode inclusion portion and having a gap between the electrode inclusion portion and a surface of the board; a pillar portion extending between the electrode inclusion portion and the board; and an overlap portion formed in the pillar portion passing through a through hole penetrating the board and overlapping an outer edge portion of the through hole on a second surface opposite to the first surface of the board.