A method for manufacturing a semiconductor optical integrated element, comprising the steps of: forming a semiconductor wafer by arranging a plurality of semiconductor optical integrated elements two-dimensionally such that optical axes of the semiconductor optical integrated elements are aligned, the semiconductor optical integrated elements each comprising a distributed feedback, DFB, laser (11, 31, 41, 51, 61, 81), an electroabsorption, EA, modulator (12, 32, 42, 52, 62, 82), and a semiconductor optical amplifier, SOA (33, 43, 53, 63, 83), that are monolithically integrated on an identical substrate and that are disposed in an order of the DFB laser, the EA modulator, and the SOA along a light emitting direction; cleaving the semiconductor wafer along a plane orthogonal to the light emitting direction to form a semiconductor bar including a plurality of the semiconductor optical integrated elements arranged one-dimensionally along a direction orthogonal to the light emitting direction such that the semiconductor optical integrated elements adjacent to each other share an identical cleavage end face as a light emission surface; inspecting each of the semiconductor optical integrated elements in a state of the semiconductor bar; and cutting off each of the semiconductor optical integrated elements of the semiconductor bar at a boundary line between the adjacent semiconductor optical integrated elements after the inspection to electrically isolate the SOA and the DFB laser from each other, wherein in the step of forming the semiconductor wafer, a connection wiring part (513d, 613d, 813d) electrically connecting the SOA and the DFB laser together is formed on each of the semiconductor optical integrated elements such that the connection wiring part straddles the boundary line between the adjacent semiconductor optical integrated elements. forming a semiconductor wafer by arranging a plurality of semiconductor optical integrated elements two-dimensionally such that optical axes of the semiconductor optical integrated elements are aligned, the semiconductor optical integrated elements each comprising a distributed feedback, DFB, laser (11, 31, 41, 51, 61, 81), an electroabsorption, EA, modulator (12, 32, 42, 52, 62, 82), and a semiconductor optical amplifier, SOA (33, 43, 53, 63, 83), that are monolithically integrated on an identical substrate and that are disposed in an order of the DFB laser, the EA modulator, and the SOA along a light emitting direction; cleaving the semiconductor wafer along a plane orthogonal to the light emitting direction to form a semiconductor bar including a plurality of the semiconductor optical integrated elements arranged one-dimensionally along a direction orthogonal to the light emitting direction such that the semiconductor optical integrated elements adjacent to each other share an identical cleavage end face as a light emission surface; inspecting each of the semiconductor optical integrated elements in a state of the semiconductor bar; and cutting off each of the semiconductor optical integrated elements of the semiconductor bar at a boundary line between the adjacent semiconductor optical integrated elements after the inspection to electrically isolate the SOA and the DFB laser from each other, wherein in the step of forming the semiconductor wafer, a connection wiring part (513d, 613d, 813d) electrically connecting the SOA and the DFB laser together is formed on each of the semiconductor optical integrated elements such that the connection wiring part straddles the boundary line between the adjacent semiconductor optical integrated elements.