PROBLEM TO BE SOLVED: To simplify a transmission mechanism of each delivery belt in a seedling tank of a seedling planter, raise the strength and carry out stable transmission. SOLUTION: The constitution of this seedling tank device of the seedling planter is characterized by installing each delivery clutch 4 for engaging and disengaging the transmission of the delivery belt 2 on the inside of a driving pulley 3 stretching the delivery belt 2 in the bottom of the seedling tank 1.