A sealing device includes a reinforcing ring and an elastic body part. The elastic body part includes an annular seal lip, an annular dust lip, and an annular side lip that extends toward an outer side on an outer periphery side of the dust lip. The side lip includes an annular middle portion that increases in diameter as progress toward the outer side and an annular distal end portion that is a portion connected to and on the outer side of the middle portion and that increases in diameter as progress toward the outer side. In the side lip, the distal end portion is bent to an inner periphery side from the middle portion. In the middle portion, at least one groove is formed annularly around an axis x.