A seedling planting device has a feed box with a joining part joined with a main frame in a fastened manner, a transmission device performing output on an operation part is accommodated in the feed box, and the joining part (90) has a joining seat part (93) formed integrally with the feed box (16), and a joining component (94) formed in a split manner from the joining seat part (94). The joining seat part (93) is joined with an upper end face (U) of the main frame (15) in a fastened manner through a riveting nut (96). An upper end side of the joining component (94) is joined with the joining seat part (93) through a joining bolt (97a) in a fastened manner, and a lower end side of the joining component (94) is joined with a rear end face (B) of the main frame (15) in a fastened manner through a joining bolt (92) towards front-and-back directions of a machine body. By adoption of the seedling planting device provided by the invention, fastened joining of the feed box relative to the main frame can be performed firmly.
