An output rod (20) of an electric clamping device includes: a tubular power transmission member (25) screw-connected to a decelerator (6); and an output rod main body (24) disposed radially inward of an inner peripheral surface of a cylindrical hole of the power transmission member (25) with a clearance between the output rod main body (24) and the inner peripheral surface. The output rod (20) further includes: a rotation preventing mechanism (26); a lock-side driving mechanism (27, 42), a release-side driving mechanism (28), and an output rod guide mechanism (29).