PURPOSE: A compact cabinet panel is provided to ensure high assemblability because the length of a main bus bar can be controlled according to the number of branch circuit breakers installed. CONSTITUTION: A main circuit breaker(10) is installed in a base panel(70). A main bus bar(40) is connected to the power output terminal of the main circuit breaker. Branch circuit breakers(20,21) are transversely arranged perpendicularly to the length of the main bus bar. A T-type bus bar(50) is integrally formed with a breaker connection bar and connected to the main bus bar through a bus bar connection bar branched downward.