The ventilation air blower is provided with: a main body housing (2) provided with an air inlet and an air outlet; a centrifugal air blower provided inside the main body housing (2) and forming an airflow that flows into the main body housing (2) from the air inlet and flows out of the main body housing (2) from the air outlet; and a first capacitor box (62) and a second capacitor box (61) that are formed as bottomed boxes each having one surface open, that store capacitors (63a, 63b) for controlling an electric motor, and that are made of a non-combustible material. The first capacitor box (62) is provided with a first planar section (64b) extending outward from the periphery of the open surface, and is attached to the outside of the main body housing (2). The second capacitor box (61) isprovided with a second planar section (64a) extending outward from the periphery of the open surface, and is embedded and installed in the main body housing (2). The open surface of the first capacitor box (62) is covered by the second planar section (64a), and the open surface of the second capacitor box (61) is covered by the first planar section (64b).