an information processing device is disclosed that is able to prevent displacement of an extension board caused by vibration or shock , and able to prevent deformation of the extension board and members nearby . the information processing device includes a substrate with a cpu mounted thereon , a housing that accommodates the substrate , an extension board arranged to be parallel to the substrate , and a supporting member that is fixed on the housing and is arranged to be parallel to at least one end surface of the substrate so that the supporting member supports the extension board .