To enable the respective effective installation of reserve seedling-carrying platforms in plural stages on both lateral sides in front of a main machine equipped with a transplanting part connected to the rear thereof without requiring another hand.

This apparatus for installing a reserve seedling-carrying platforms comprises respective supporting rail units 1 and 1, horizontally extended in the front and rear directions and installed on both lateral sides in front of a main machine A equipped with a transplanting part B connected to the rear thereof, both vertically stood movable rail units 2 and 2, respectively vertically movable back and forth along both the supporting rail units 1 and 1, fixable thereto and respectively installed connectedly to both the supporting rails 1 and 1 and supporting parts 4 and 4, respectively movable vertically along both the movable rail units 2 and 2, fixable thereto, provided with supporting plates 3 and 3 horizontally extended in the front and rear directions of the machine body and arranged in both the movable rail units 2 and 2 so as to enable the installation of both the reserve seedling supporting frame pedestals 6 on both outer lateral sides of the front of the machine body while inserting the supporting plates 3 and 3 under the reserve seedling supporting frame pedestals 6 having plural reserve seedling-carrying platforms 5 on the upper and lower sides and lifting the reserve seedling supporting frame pedestals 6 with the supporting plates 3 and 3.