An engine-driven power generator apparatus, which includes, within a case, an engine and a power generator drivable with the engine, and in which an operation panel is provided on a front cover and an air intake louver for introducing air into the case is provided within the case, includes: a waterproof cover covering the operation panel and the air intake louver; an air guide passage of a labyrinth shape provided within the waterproof cover and communicating the outside of the waterproof cover with the air intake louver; and a brush-shaped water separation unit provided in the air guide passage and having a plurality of pins projecting in a direction intersecting flows of air in the air guide passage.