A bearing unit (90) for rotatably supporting a shaft (100) comprises a seamless holding member (120) with a gap allowing a shaft to run through and extend to the outside, a bearing (130) arranged in the inside of the holding member to rotatably support the shaft so as to make it radially revolvable, an anti-shaft-release member (115) fitted to the shaft so as to abut the bearing in order to prevent the shaft from slipping away in the thrusting direction and a space-forming member (113) arranged in the inside of the holding member so as to secure a space around the anti-shaft-release member. A bearing unit may further comprise an lubricating oil seal member and the space-forming member may be used to form a passage way for lubricating oil to prevent lubricating oil from leaking.