A rolling bearing comprising an outer bearing race and an inner bearing race defining a bearing space between the outer bearing race and the inner bearing race, rolling elements mounted in the bearing space, and a seal device provided at one of axial openings of the bearing space and including a ring member formed of a metal or a resin and formed with through holes, wherein one of the outer bearing race and the inner bearing race constitutes a stationary bearing race, and the other of the outer bearing race and the inner bearing race constitutes a rotatable bearing race; wherein the ring member is in engagement with the stationary bearing race; wherein the through holes are provided on a side portion of the ring member and are configured such that lubricating oil can pass through the through holes and solid foreign substances cannot pass through the through holes, wherein the seal device further includes a sub-ring member formed of a metal or a resin and fixed to the rotatable bearing race, wherein the sub-ring member includes: a fitting portion fitted in a fitting recess formed in the rotatable bearing race with an interference fit; and a side portion extending from the fitting portion of the sub-ring member so as to be integral with the fitting portion, wherein the ring member includes: a fitting portion fitted in a fitting recess (1b, 1e) formed in the stationary bearing race with an interference fit; a side portion extending from the fitting portion of the ring member so as to be integral with the fitting portion; a plate-shaped relief portion at the distal edge of the ring member opposed to the rotatable bearing race, the relief portion having surfaces extending parallel to the surfaces of the side portion of the ring member; and a connecting portion disposed between the side portion of the ring member and the relief portion and inclined toward the rolling elements and toward the relief portion, wherein a labyrinth seal is defined by a gap between the relief portion and the connecting portion, of the ring member, and the fitting portion and the side portion, of the sub-ring member. a fitting portion fitted in a fitting recess formed in the rotatable bearing race with an interference fit; and a side portion extending from the fitting portion of the sub-ring member so as to be integral with the fitting portion, wherein the ring member includes: a fitting portion fitted in a fitting recess (1b, 1e) formed in the stationary bearing race with an interference fit; a side portion extending from the fitting portion of the ring member so as to be integral with the fitting portion; a plate-shaped relief portion at the distal edge of the ring member opposed to the rotatable bearing race, the relief portion having surfaces extending parallel to the surfaces of the side portion of the ring member; and a connecting portion disposed between the side portion of the ring member and the relief portion and inclined toward the rolling elements and toward the relief portion, wherein a labyrinth seal is defined by a gap between the relief portion and the connecting portion, of the ring member, and the fitting portion and the side portion, of the sub-ring member. a fitting portion fitted in a fitting recess (1b, 1e) formed in the stationary bearing race with an interference fit; a side portion extending from the fitting portion of the ring member so as to be integral with the fitting portion; a plate-shaped relief portion at the distal edge of the ring member opposed to the rotatable bearing race, the relief portion having surfaces extending parallel to the surfaces of the side portion of the ring member; and a connecting portion disposed between the side portion of the ring member and the relief portion and inclined toward the rolling elements and toward the relief portion, wherein a labyrinth seal is defined by a gap between the relief portion and the connecting portion, of the ring member, and the fitting portion and the side portion, of the sub-ring member.