To solve the problem that as seedling culture boxes applied with a series of sowing work are stacked when the seedling culture boxes are stopped, an impact is applied, and bed soil and covering soil may be displaced, thus causing an obstacle to efficiency and high speed.

The seedling culture boxes conveyed by a conveyance roller 16 are abutted on a leaf spring member 26 at a conveyance terminal end E. The leaf spring member 26 smoothly absorbs the impact by sliding and moving a lower end thereof on a fixed member and elastically deforming its curved part. When lifting the seedling culture boxes by lifting mechanisms 27, 30, 31, the leaf spring member biases the seedling culture boxes so that they are abutted on a front end regulating plate 21 over an entire lifting stroke.