PROBLEM TO BE SOLVED: To provide a seedling-planting mechanism of a rice transplanter, which can smoothly perform sliding operation for a seedling pushing tool. ! SOLUTION: There is provided a seedling-planting mechanism of a rice transplanter, in which a seedling pushing tool 31 for pushing seedlings from a seedling-planting tine 8 is supported on a planting tine-supporting case 10 slidably in a state projecting outward from the inside of the planting tine-supporting case 10 for supporting the seedling-planting tine 8, a moving operation mechanism 32 for moving the seedling pushing tool 31 to an action position or a non-action position accompanied by the seedling-planting movement operation of the planting tine-supporting case 10 is disposed in the inside of the planting tine-supporting case 10, the seedling pushing tool 31 is slidably supported on the planting tine-supporting case 10 with a sliding portion 33a on a tine tip end side placed on the seedling-pushing side in the moving direction and a sliding support portion 33b on a base end side placed on the side opposite to the seedling-pushing side, respectively. ! COPYRIGHT: (C)2014,JPO&INPIT