An electronic device system comprises a portable computer including an input surface through which information is input, a power switch manually turned on or off, and a first connector electrically connected to the power switch, and an expansion station having an expansion device for expanding a function of the computer and an input section connected to a power supply. The expansion station include a main body containing the expansion device and the input section, a stand supported by the main body and removably holding the computer, and a second connector arranged in the stand and connected to the first connector when the computer is held by the stand. The stand includes a pair of engaging members movable between a first position, in which they hook the computer, and a second position, in which they are released from the computer, when the first and second connectors are connected to each other, and lock means movable between a lock position, in which the engaging members are inhibited from being moved from the first position to the second position, and a lock release position, in which the engaging members are allowed to move from the first position to the second position. The lock means is maintained in the lock position, when the computer is connected to the power supply through the first and second connectors and the power switch is turned on.