An air-sending device comprising: - a housing including an inlet air passage and an outlet air passage, the inlet air passage communicating with an air inlet disposed at one side of the housing, the outlet air passage communicating with an air outlet; - a first partition plate partitioning an interior of the housing into the inlet air passage and the outlet air passage; - a bell mouth disposed around an opening defined in the first partition plate; and - an impeller disposed over the first partition plate with the bell mouth interposed between the impeller and the first partition plate, the impeller having a rotation axis that extends in a direction that intersects the first partition plate, - the impeller being configured to suction air into the inlet air passage from the air inlet, blow out air in a circumferential direction of the impeller, and blow out air from the air outlet through the outlet air passage, - the inlet air passage having a width greater than an outside diameter of the impeller, the inlet air passage guiding air from the air inlet along the first partition plate to the opening of the first partition plate, and having an air-passage wall (9-1 to 9-6, 12), the air-passage wall being located at a position in the inlet air passage that is past a center of the opening along the first partition plate from the air inlet, characterised by - the air-passage wall (9-1 to 9-6, 12) being equal in width to the inlet air passage and the air-passage wall being equal in dimension along the rotation axis to the inlet air passage, and - at an inlet of the bell mouth, a distance from the rotation axis of the impeller to the air-passage wall being less than a distance from the rotation axis of the impeller to an end portion of the bell mouth that is close to the air inlet; such that air is prevented from entering the impeller from an area located farther from the air inlet than is the air-passage wall (9-1 to 9-6, 12). - a housing including an inlet air passage and an outlet air passage, the inlet air passage communicating with an air inlet disposed at one side of the housing, the outlet air passage communicating with an air outlet; - a first partition plate partitioning an interior of the housing into the inlet air passage and the outlet air passage; - a bell mouth disposed around an opening defined in the first partition plate; and - an impeller disposed over the first partition plate with the bell mouth interposed between the impeller and the first partition plate, the impeller having a rotation axis that extends in a direction that intersects the first partition plate, - the impeller being configured to suction air into the inlet air passage from the air inlet, blow out air in a circumferential direction of the impeller, and blow out air from the air outlet through the outlet air passage, - the inlet air passage having a width greater than an outside diameter of the impeller, the inlet air passage guiding air from the air inlet along the first partition plate to the opening of the first partition plate, and having an air-passage wall (9-1 to 9-6, 12), the air-passage wall being located at a position in the inlet air passage that is past a center of the opening along the first partition plate from the air inlet, characterised by - the air-passage wall (9-1 to 9-6, 12) being equal in width to the inlet air passage and the air-passage wall being equal in dimension along the rotation axis to the inlet air passage, and - at an inlet of the bell mouth, a distance from the rotation axis of the impeller to the air-passage wall being less than a distance from the rotation axis of the impeller to an end portion of the bell mouth that is close to the air inlet;