A safety control system for realizing functional safety, the safety control system comprising: a computation processing unit configured to execute a safety program; and an access management unit configured to receive a command for updating a value of one of stored variables through secure communication from an external device, and update the stored variable in response to an access from the external device, wherein the computation processing unit is connected to the access management unit via a local bus, wherein the safety control system comprises a standard control unit responsible for standard control and a safety control unit responsible for safety control, the computation processing unit is provided in the safety control unit, and the access management unit is provided in the standard control unit, wherein the update of the stored variables is reflected between the standard control unit and the safety control unit via the local bus, and the computation processing unit is configured to start execution of the safety program when a specific variable among the stored variables is updated to a predefined value by the access management unit, wherein the predefined value is zero representing false, the safety control system being characterized in further comprising: an attribute setting receiving unit configured to receive a setting of one or a plurality of attributes for the stored variables managed by the safety control system, wherein the one or plurality of attributes includes a setting of validity/invalidity of security, wherein the access management unit uses the secure communication for exchange of the command for updating a value of the variable of which the security is set to validity, wherein when a user operation is performed with respect to the external device, a value indicating the user operation is transmitted to the standard control unit through the secure communication between the external device and the standard control unit; the standard control unit is configured to update a corresponding stored variable with the value indicating the user operation from the external device; the standard control unit and the safety control unit are configured to periodically execute data refresh to update the value of the stored variable in the safety control unit with an updated value of the stored variable in the standard control unit; and when the stored variable in the safety control unit is updated to the predefined value of the safety program, the safety control unit is configured to start execution of the safety program. a computation processing unit configured to execute a safety program; and an access management unit configured to receive a command for updating a value of one of stored variables through secure communication from an external device, and update the stored variable in response to an access from the external device, wherein the computation processing unit is connected to the access management unit via a local bus, wherein the safety control system comprises a standard control unit responsible for standard control and a safety control unit responsible for safety control, the computation processing unit is provided in the safety control unit, and the access management unit is provided in the standard control unit, wherein the update of the stored variables is reflected between the standard control unit and the safety control unit via the local bus, and the computation processing unit is configured to start execution of the safety program when a specific variable among the stored variables is updated to a predefined value by the access management unit, wherein the predefined value is zero representing false, the safety control system being characterized in further comprising: an attribute setting receiving unit configured to receive a setting of one or a plurality of attributes for the stored variables managed by the safety control system, wherein the one or plurality of attributes includes a setting of validity/invalidity of security, wherein the access management unit uses the secure communication for exchange of the command for updating a value of the variable of which the security is set to validity, wherein when a user operation is performed with respect to the external device, a value indicating the user operation is transmitted to the standard control unit through the secure communication between the external device and the standard control unit; the standard control unit is configured to update a corresponding stored variable with the value indicating the user operation from the external device; the standard control unit and the safety control unit are configured to periodically execute data refresh to update the value of the stored variable in the safety control unit with an updated value of the stored variable in the standard control unit; and when the stored variable in the safety control unit is updated to the predefined value of the safety program, the safety control unit is configured to start execution of the safety program.