A series hybrid type straddled vehicle (1, 100, 200, 300) comprising: a frame body (11, 111, 211, 311) that constitutes a frame structure; a rear arm (31, 231, 331) that is supported in a swingable manner by the frame structure (10, 110, 210, 310); a driving wheel (32, 132, 232, 332) that is supported in a rotatable manner by the rear arm (31, 231, 331); a drive motor (51, 251, 351) that is supported by the frame structure (10, 110, 210, 310) or the rear arm (31, 231, 331), the drive motor (51, 251, 351) being configured to drive the driving wheel (32, 132, 232, 332); and an electric power generation unit (40, 140, 240, 340) including an electric power generation engine and an electric power generator, characterized in that the electric power generation engine is arranged off-set toward a first direction from the center of the series hybrid type straddled vehicle (1, 100, 200, 300) with respect to a left-right direction of the series hybrid type straddled vehicle (1, 100, 200, 300), provided that the left-right direction is composed of the first direction and a second direction opposite to the first direction, the electric power generation engine being positioned so as not to overlap the drive motor (51, 251, 351) when viewed in the left-right direction, the electric power generator being positioned farther in the second direction than the electric power generation engine, the electric power generator being arranged so as to have an overlap with the electric power generation engine when viewed in the left-right direction, the electric power generator being arranged so as not to overlap the drive motor (51, 251, 351) when viewed in the left-right direction, the electric power generator being driven by the electric power generation engine to generate electric power for driving the drive motor (51, 251, 351), the electric power generation unit (40, 140, 240, 340) being unsupported by the rear arm (31, 231, 331) but instead supported by the frame body (11, 111, 211, 311) such that the electric power generation unit (40, 140, 240, 340) constitutes the frame structure (10, 110, 210, 310) or does not constitute the frame structure (10, 110, 210, 310). a frame body (11, 111, 211, 311) that constitutes a frame structure; a rear arm (31, 231, 331) that is supported in a swingable manner by the frame structure (10, 110, 210, 310); a driving wheel (32, 132, 232, 332) that is supported in a rotatable manner by the rear arm (31, 231, 331); a drive motor (51, 251, 351) that is supported by the frame structure (10, 110, 210, 310) or the rear arm (31, 231, 331), the drive motor (51, 251, 351) being configured to drive the driving wheel (32, 132, 232, 332); and an electric power generation unit (40, 140, 240, 340) including an electric power generation engine and an electric power generator, characterized in that the electric power generation engine is arranged off-set toward a first direction from the center of the series hybrid type straddled vehicle (1, 100, 200, 300) with respect to a left-right direction of the series hybrid type straddled vehicle (1, 100, 200, 300), provided that the left-right direction is composed of the first direction and a second direction opposite to the first direction, the electric power generation engine being positioned so as not to overlap the drive motor (51, 251, 351) when viewed in the left-right direction, the electric power generator being positioned farther in the second direction than the electric power generation engine, the electric power generator being arranged so as to have an overlap with the electric power generation engine when viewed in the left-right direction, the electric power generator being arranged so as not to overlap the drive motor (51, 251, 351) when viewed in the left-right direction, the electric power generator being driven by the electric power generation engine to generate electric power for driving the drive motor (51, 251, 351), the electric power generation unit (40, 140, 240, 340) being unsupported by the rear arm (31, 231, 331) but instead supported by the frame body (11, 111, 211, 311) such that the electric power generation unit (40, 140, 240, 340) constitutes the frame structure (10, 110, 210, 310) or does not constitute the frame structure (10, 110, 210, 310).