The present invention provides a single-bearing reel which prevents the invasion of the water towards the periphery of a spool shaft. The single-bearing reel includes a support unit (5), a spool (3), an annular first restriction member (11), an annular second restriction member (12), a pair of O-shaped rings (31), a second seal member (32) and a third seal member (33). The support unit 5 rotates freely relative to the spool shaft 2, and the spool 3 is assembled on the support unit 5. The first and second restriction members are configured at the periphery of the support unit 5 partially at the two end sides of the support unit 5. The O-shaped rings 31 seal between the support unit 5 and the first and second restriction members 11, 12. The second seal member (32, 132) seals an inner peripheral part of the support unit from an inner peripheral part of the first restriction member. A third seal member (33, 133) seals the inner peripheral part of the support unit from an inner peripheral part of the second restriction member.