A car alarm apparatus includes a first horn; a second horn; an electrical source; a theft detection section; a horn switch; a first relay closed when the horn switch is operated; a first fuse connected to the electrical source in series with the first relay and the first horn; a second fuse connected to the electrical source separately from the first fuse; and a second relay connected to the electrical source in series with the second fuse and the second horn, wherein the second relay includes a first contact that connects the second horn to an electrical source through the first fuse and the first relay in parallel with the first horn and a second contact that connects the second horn to the electrical source through the second fuse, and closes the second contact when the occurrence of the theft is detected.