A sealing device includes a reinforcing ring formed annularly around an axis and an elastic body part that is formed from an elastic body attached to the reinforcing ring and that is formed annularly around the axis. The reinforcing ring includes a tubular portion having a cylindrical shape around the axis and a flange projecting annularly from an outer end portion of the tubular portion to an inner periphery side. The elastic body part includes a lip portion that is an annular portion covering the flange from an outer side, projecting from the flange toward the outer side in a direction of the axis, and projecting toward the inner periphery side in a radial direction. The lip portion includes a seal lip portion that is an annular portion projecting toward the outer side in the direction of the axis and a secondary lip portion that is an annular portion projecting toward an inner side in the direction of the axis.