To provide a transmission structure of a rice transplanter capable of simplifying a structure, reducing blowoff of an oil from a breather and decreasing the power loss when traveling without operation by arranging a transplanting clutch at an input part of a transplanting transmission system.

This transmission structure is constituted so that the power from a traveling transmission system after changing the speed may be transmitted through a transplanting transmission system U comprising a transplanting clutch 22 and a device 23 for changing the speed between to roots to a seedling- transplanting device 3, and the transplanting clutch 22 is arranged at an input part Ua in the transplanting transmission system U at the upstream side of the transmission from the device 23 for changing the speed between the roots. A transmission case 7 enclosing each transmission for the traveling transmission system S and the transplanting transmission system U is preferably arranged at the rear part of the mobile machine body. Further, a manuring device 26 is preferably loaded, and the front side terminal of a power taking up axis 25 for transplanting in the transplanting transmission system U is preferably utilized as a power-taking out axis for manuring by extending the power-taking out axis for manuring from the mission case 7.