A lock device includes a lock cover, a restricting portion, a drive source, a biasing portion, and a pressing portion. The lock cover is opened and closed when a developer storing portion storing developer is attached or detached. The restricting portion, when the lock cover is closed, is engaged with the lock cover in such a way as to restrict the lock cover from being opened. The drive source drives the restricting portion in such a way as to release an engagement between the restricting portion and the lock cover. The biasing portion biases the restricting portion in a direction opposite to a direction in which the drive source drives the restricting portion. The pressing portion presses the lock cover in an opening direction in conjunction with an operation of the drive source to release the engagement between the restricting portion and the lock cover.