A current sensor configured to detect electric current flowing through an object to be measured in a state where the current sensor encloses the object to be measured includes a coil body configured to detect the electric current flowing through the object to be measured, and a holding portion to which a base end portion of the coil body is attached, the holding portion being configured to insert and hold a leading end 1a of the coil body in an insertion port. A part having a greater curvature than a curvature of the base end portion is formed in a leading end portion having the leading end of the coil body.