A method for manufacturing a pressure-sensitive sensor includes providing an extruder that includes a cylindrical die, a mandrel arranged inside the die and having plural helical grooves on an outer circumferential surface, and an annular outlet sandwiched between the die and the mandrel, and by using the extruder, performing simultaneous extrusion-molding of an elastic insulating material and an elastic conductive material by supplying the elastic conductive material into not less than two of the grooves from the inside of the mandrel while extruding the elastic insulating material, so as to form a pressure-sensitive sensor. The sensor includes a tubular body including an elastic insulation and having a hollow portion along a longitudinal direction, and not less than two conductive ribs including an elastic conductor and helically provided along an inner circumferential surface of the hollow portion of the tubular body so as to protrude inward from the inner circumferential surface.