PROBLEM TO BE SOLVED: To provide the subject structure for mounting capable of rapidly and accurately mounting an auxiliary deck by simple operations and reducing the production cost by installing a guide for positioning for mounting the auxiliary deck at a specific position. SOLUTION: This structure has a constitution in which a planting part for multirow planting is additionally installed at the rear of a mobile part of a rice transplanter, a rear car body cover forming a floor or a step around a driver's seat is placed on a car body frame and an auxiliary deck 130 is arranged on the left and right outside of the rear car body cover. Supporting stays 201 and 202 for placing the auxiliary deck 130 are extended from the car body frame to the lateral side and a guide 204 for positioning for mounting the auxiliary deck 130 is arranged among the supporting stays 201 and 202 and the auxiliary deck 130.
