Abstract: A gear component has an annular form, is made of a metal, and includes tooth portions and a support portion which supports the tooth portions. The tooth portions are provided on an outside of the support portion along an entire circumference thereof, and groove portions are provided along a width direction of the gear component evenly on an annular inner surface of the support portion. At least one groove portion is provided per one tooth portion or two or more adjacent tooth portions, and each groove portion is located to correspond to a position where one tooth portion is present on the support portion.