A straddled vehicle comprising: a vehicle body frame; an engine pivotably supported by the vehicle body frame; a storage box disposed above the engine in a vehicle up-and-down direction; a seat disposed above the storage box in the vehicle up-and-down direction; an intake pathway portion disposed below the storage box in the vehicle up-and-down direction, the intake pathway portion being connected to the engine; and a tensioner disposed between the intake pathway portion and the engine in the vehicle up-and-down direction, the tensioner being attached to the engine, wherein the tensioner includes a first accommodation portion disposed outside the engine, the first accommodation portion being attached to the engine, a second accommodation portion disposed inside the engine, the second accommodation portion being connected to the first accommodation portion, characterized in that the tensioner further includes a first shaft at least in part disposed inside the first accommodation portion, the first shaft including a first threaded portion, a second shaft at least in part disposed inside the second accommodation portion, the second shaft being moved in an axis direction of the tensioner in accordance with rotation of the first shaft, the second shaft including a second threaded portion and a distal end, the second threaded portion being screwed with the first threaded portion, the distal end protruding from the second accommodation portion into the engine, and a spring urging the first shaft to rotate the first shaft, the tensioner at least in part overlaps with the intake pathway portion as seen in a vehicle plan view, and the spring is disposed inside the first accommodation portion and the second accommodation portion. a vehicle body frame; an engine pivotably supported by the vehicle body frame; a storage box disposed above the engine in a vehicle up-and-down direction; a seat disposed above the storage box in the vehicle up-and-down direction; an intake pathway portion disposed below the storage box in the vehicle up-and-down direction, the intake pathway portion being connected to the engine; and a tensioner disposed between the intake pathway portion and the engine in the vehicle up-and-down direction, the tensioner being attached to the engine, wherein the tensioner includes a first accommodation portion disposed outside the engine, the first accommodation portion being attached to the engine, a second accommodation portion disposed inside the engine, the second accommodation portion being connected to the first accommodation portion, characterized in that the tensioner further includes a first shaft at least in part disposed inside the first accommodation portion, the first shaft including a first threaded portion, a second shaft at least in part disposed inside the second accommodation portion, the second shaft being moved in an axis direction of the tensioner in accordance with rotation of the first shaft, the second shaft including a second threaded portion and a distal end, the second threaded portion being screwed with the first threaded portion, the distal end protruding from the second accommodation portion into the engine, and a spring urging the first shaft to rotate the first shaft, the tensioner at least in part overlaps with the intake pathway portion as seen in a vehicle plan view, and the spring is disposed inside the first accommodation portion and the second accommodation portion.