A pushing-out apparatus for an extendible mast comprising: a mast storing unit which is configured to store an extendible mast including plural stages of foldable trusses in a state that the plural stages are folded; a mast pushing-out unit which is configured to be stored in the mast storing unit around the extendible mast stored in the mast storing unit in the state the plural stages are folded; and a mast pushing-out driving unit which is configured to move the mast pushing-out unit in a moving direction to a predetermined projecting position in an outside of the mast storing unit while the plural stages of the extendible mast are folded, to sequentially extend out the plural folded stages of the extendible mast stored in the mast storing unit by the mast pushing-out unit of the projecting position from the mast storing unit and to push out the extended stages from the mast pushing-out unit of the projecting position in a side of the mast pushing-out unit opposing to the mast storing unit, characterized in that the mast pushing-out driving unit includes lead screws each of which has a rotational center line extending in the moving direction of the mast pushing-out unit, which are provided in the mast pushing-out unit to be rotational on the rotational center line, and which are able to engage with the plural stages of the extendible mast stored in the mast storing unit, a bi-directional rotation driving source which is provided in one of the mast storing unit and the mast pushing-out unit and which selectively rotates the lead screws in one or another direction (B or C), and a selectively fixing unit which selectively fixes the mast pushing-out unit arrived at the projecting position to the projecting position, and while the bi-directional rotation driving source rotates the lead screws in one direction, the lead screws move the mast pushing-out unit from the mast storing unit to the projecting position, together with a stage included in the plural folded stages of the extendible mast in the mast storing unit and located in a tip end of the moving direction, and extend out the tip end stage in the mast pushing-out unit, and while the bi-directional rotation driving source rotates the lead screws in the other direction after the mast pushing-out unit is moved to the projecting position, the lead screws sequentially push out and extend out the plural stages following the tip end stage included in the plural folded stages of the extendible mast in the mast storing unit, and sequentially push out the extended stages following the tip end extended stage from the mast pushing-out unit to an outside of the mast pushing-out unit. a mast storing unit which is configured to store an extendible mast including plural stages of foldable trusses in a state that the plural stages are folded; a mast pushing-out unit which is configured to be stored in the mast storing unit around the extendible mast stored in the mast storing unit in the state the plural stages are folded; and a mast pushing-out driving unit which is configured to move the mast pushing-out unit in a moving direction to a predetermined projecting position in an outside of the mast storing unit while the plural stages of the extendible mast are folded, to sequentially extend out the plural folded stages of the extendible mast stored in the mast storing unit by the mast pushing-out unit of the projecting position from the mast storing unit and to push out the extended stages from the mast pushing-out unit of the projecting position in a side of the mast pushing-out unit opposing to the mast storing unit, characterized in that the mast pushing-out driving unit includes lead screws each of which has a rotational center line extending in the moving direction of the mast pushing-out unit, which are provided in the mast pushing-out unit to be rotational on the rotational center line, and which are able to engage with the plural stages of the extendible mast stored in the mast storing unit, a bi-directional rotation driving source which is provided in one of the mast storing unit and the mast pushing-out unit and which selectively rotates the lead screws in one or another direction (B or C), and a selectively fixing unit which selectively fixes the mast pushing-out unit arrived at the projecting position to the projecting position, and while the bi-directional rotation driving source rotates the lead screws in one direction, the lead screws move the mast pushing-out unit from the mast storing unit to the projecting position, together with a stage included in the plural folded stages of the extendible mast in the mast storing unit and located in a tip end of the moving direction, and extend out the tip end stage in the mast pushing-out unit, and while the bi-directional rotation driving source rotates the lead screws in the other direction after the mast pushing-out unit is moved to the projecting position, the lead screws sequentially push out and extend out the plural stages following the tip end stage included in the plural folded stages of the extendible mast in the mast storing unit, and sequentially push out the extended stages following the tip end extended stage from the mast pushing-out unit to an outside of the mast pushing-out unit.