To provide a shaft device with a bearing manufacturable at low cost by easily assembling block bodies such as cam blocks and the inner ring of a rolling bearing onto the outer diameter surface of a shaft in the axial direction.

This shaft device includes the shaft 12, the block bodies 16, and the rolling bearing 31. The block bodies 16 and the inner ring 32 of the rolling bearing 31 are axially fitted to the outer diameter surface of the shaft 12 in this order and disposed at predetermined intervals. A rotation stop part 20 for stopping the rotation of the inner ring 32 of the rolling bearing 31 around the axis of the shaft 12 by the engagement thereof is formed between the outer diameter surface of the shaft 12 and the inner ring 32 of the rolling bearing 31.