An information processing apparatus includes a lower unit having a circuit board on which first electronic components are mounted and also having a chassis in which the circuit board is mounted at a bottom, an upper surface of the chassis being open; and an upper unit having a tray member detachably attached to the chassis and also having second electronic components mounted at a bottom of the tray member, the upper unit being stacked on the lower unit; wherein the upper unit has a connector board attached to the tray member, having a first and a second connectors, the first connector being fitted to a board-side connector on the circuit board, the second connector being electrically connected to the second electronic components, and an opening is formed at the bottom of the tray member, the first connector and the board-side connector being mutually fitted through the opening.