There is disclosed a seedling transplanter comprising a seedling planting unit (40) vertically movably provided on a traveling vehicle body (2)； a planting operation member (36) for switching on/off the lifting/lowering operation and actuation of the said seedling planting unit (40)； a turn coordinating actuator (110) for forcibly operating the said planting operation member (36)； a controller (200) for coordinating a turn, in coordination with the turning of the said traveling vehicle body (2), by actuating the turn coordinating actuator (110) and operating the start of the lowering and actuation of the said seedling planting unit (40)； a lifting mechanism of seedling planting unit (50) for, in coordination with the turning operation of the traveling vehicle body (2), bringing the seedling planting unit (40) into the non-operation state and lifting the same； and a movement detection member (171, 172) for detecting the rotating speed of a wheel (5) of the traveling vehicle body (2). The control device (200) lowers the seedling planting unit (40) based on the rotating speed of the wheel (5) detected by the movement detection member (171, 172), and if the movement detection member (171, 172) does not detect a set rotating speed within a given time after the seedling planting unit (40) lowers, or after the movement detection member (171, 172) detects a set rotating speed and brings the seedling planting unit (40) into the operation state, drives the turn coordinating actuator (110) in a reverse direction, such that the planting operation member (36) switched to the "down" or "plant" position manually switchable to the "up" position.
