An attitude adjusting device (1) comprises a first roller (3), a second roller (5), a first stopper (7) and a second stopper (9). A golf ball (G) having a spew (B) is mounted on the first roller (3) and the second roller (5). Each of the first roller (3) and the second roller (5) includes a portion (11) having a small diameter. A groove (13) is formed on the surface of the portion (11) having a small diameter. With the rotations of the first roller (3) and the second roller (5), the golf ball (G) is rolled. When the spew (B) abuts on either or both of the first stopper (7) and the second stopper (9), the rolling is stopped. In a state in which the rolling is stopped, the spew (B) is extended in a horizontal direction. By the portion (11) having a small diameter and the groove (13), the rolling of the golf ball (G) is promoted.