PROBLEM TO BE SOLVED: To provide a seedling transplanter capable of reducing labor and time required for switch operation of preliminary seedling frames, and performing posture change of the preliminary seedling frames and keeping a balance by moving a center of gravity of a machine body at a sloping land or the like.SOLUTION: The seedling transplanter includes a planting device 5 provided at a rear part of a travel vehicle body 2 via a lifting/lowering link mechanism 4 and can be switched between: a stacked form A in which preliminary seedling mounts 6 with preliminary mat seedlings mounted thereon are stacked in vertical plural stages on a front side of the travel vehicle body 2 and a developed form B in which the preliminary seedling mounts are arranged front and rear. In linkage with lifting/lowering of the planting device 5 by the lifting/lowering link mechanism 4, the preliminary seedling mounts 6 are switched to the stacked form A or developed form B. When an inclination sensor 7 detects a front lifting inclination of the travel vehicle body 2 and a lifting/lowering sensor 8 detects the planting device 5 positioned at a lifted position, a drive motor 9 switches the preliminary seedling mounts 6 to the developed form B.
