PURPOSE: To provide a high collection ratio and proper rigidity after development by arranging a plurality of pairs of extension masts consisting of a primary series of a plurality of members, extendable parabolically toward the same direction, in a developing antenna mounted in a satellite.

CONSTITUTION: For developing a developing antenna in a storage condition, actuators 15 installed to the respective corner parts of a central hub 0 constructed of polygonal plate type conductive plate are driven, and a driving pulley 16 is rotated so as to rotate a developing synchronous pulley 8a on a hinge 7a. Because of this rotation, the adjacent synchronous pulley 8c is turned via a synchronous cable 9a. Subsequently, synchronous pulleys 8e, 8f are turned in the similar way, and extension mass including mast members 6a-6d are developed parabolically substantially, so that a mesh folded between the mast members 6a-6d is developed simultaneously, and then, development of the antenna is completed.