A covers opening/closing sequence regulation system includes a first cover and a second cover openably and closably attached to a housing. The first and second covers are provided in a way that the first cover becomes openable and closable while the second cover is in a fully-closed state, and that the second cover becomes unable to be fully-closed from an opened state while the first cover is in a fully-closed state. A regulation mechanism is configured to stop the first cover in a spaced-out position, which is spaced out from a fully-closed position of the first cover, in an operation of closing the first cover toward the fully-closed position with the second cover being in an opened state. The second cover is openable and closable while the first cover is in the spaced-out position.