In the imaging unit, the first optical system holding frame 21 and the second optical system holding frame 22 are relatively movable in a direction perpendicular to the optical axis O of the photographing light incident on the first objective lens groups 41 and 42. The second optical system holding frame 22 and the third optical system holding frame 23 are relatively movable in the direction along the optical axis O of the photographing light incident on the solid-state imaging device 51, and a predetermined optical system is used during assembly. The performance can be adjusted.撮像ユニットは、第１の光学系保持枠２１と第２の光学系保持枠２２とが第１の対物レンズ群４１，４２に入射される撮影光の光軸Ｏに直交する方向へ相対移動自在とし、第２の光学系保持枠２２と第３の光学系保持枠２３とが固体撮像素子５１に入射される撮影光の光軸Ｏに沿った方向に相対移動自在とし、組み付け時に所定の光学性能調整を行なえるようにした。
