A data access device (1, 2) comprising: a bus slave; and a bus master that notifies the bus slave of a bus request and makes an access to the bus slave, characterized in that: the bus request includes mode information for selecting whether error notification for the access is performed by the bus slave or the bus master, wherein, in a case where the mode information indicating that error notification is performed by the bus slave is included in the bus request, when an error for the access in the bus request has occurred, the bus slave performs error notification, wherein, in a case where the mode information indicating that error notification is performed by the bus master is included in the bus request, when an error for the access in the bus request has occurred, the bus slave sends error information to the bus master, wherein, in a case of making a speculative load access, the bus master makes the bus request include the mode information indicating that error notification is performed by the bus master, and wherein, in a case where execution of an instruction of the speculative load access has been fixed and the error information for the load access has been received from the bus slave, the bus master performs error notification. a bus slave; and a bus master that notifies the bus slave of a bus request and makes an access to the bus slave, characterized in that: the bus request includes mode information for selecting whether error notification for the access is performed by the bus slave or the bus master, wherein, in a case where the mode information indicating that error notification is performed by the bus slave is included in the bus request, when an error for the access in the bus request has occurred, the bus slave performs error notification, wherein, in a case where the mode information indicating that error notification is performed by the bus master is included in the bus request, when an error for the access in the bus request has occurred, the bus slave sends error information to the bus master, wherein, in a case of making a speculative load access, the bus master makes the bus request include the mode information indicating that error notification is performed by the bus master, and wherein, in a case where execution of an instruction of the speculative load access has been fixed and the error information for the load access has been received from the bus slave, the bus master performs error notification. the bus request includes mode information for selecting whether error notification for the access is performed by the bus slave or the bus master, wherein, in a case where the mode information indicating that error notification is performed by the bus slave is included in the bus request, when an error for the access in the bus request has occurred, the bus slave performs error notification, wherein, in a case where the mode information indicating that error notification is performed by the bus master is included in the bus request, when an error for the access in the bus request has occurred, the bus slave sends error information to the bus master, wherein, in a case of making a speculative load access, the bus master makes the bus request include the mode information indicating that error notification is performed by the bus master, and wherein, in a case where execution of an instruction of the speculative load access has been fixed and the error information for the load access has been received from the bus slave, the bus master performs error notification.