An image forming apparatus with a plurality of units operatively connected together is disclosed. A main power switch is mounted on one side wall of a copier body unit while a paper discharge unit next to the copier body unit is formed with a recess facing the main power switch. The recess defines an opening only great enough for a person to touch the main power switch with a fingertip. Even when the different units are combined without any clearance therebetween, the main power switch can be operated via the above opening. In addition, the main power switch is not easily visible and can therefore be prevented from being inadvertently turned off.