In an information processing apparatus for performing user certification when an OS starts based on security key information of security hardware, a need has arisen to restore the security key information before replacement of the security hardware replaced for troubleshooting. The conveyor device includes a pair of conveying surfaces for conveying the circuit boards and a pair of board supports for supporting one of the circuit boards. The integral retaining ring includes at least three recesses and the chamber ring includes at least three bolts able to penetrate into the recesses in order to lock the retaining ring on the chamber ring.