A safety device comprising: a first computation unit (32, 32a, 32b) configured to perform a first computation on a detected value that is detected from a subject to be controlled, thus obtaining a first result value; a second computation unit (33, 33a, 33b) configured to perform a second computation on the detected value, thus obtaining a second result value, and determine whether the first result value is equal to the second result value; an output control unit configured to output the first result value in a case that the second computation unit (33, 33a, 33b) determines that the first result value is equal to the second result value, the output control unit being configured not to output the first result value in a case that the second computation unit (33, 33a, 33b) determines that the first result value is not equal to the second result value; and a first central processing device including the first computation unit (32, 32a, 32b) and the second computation unit (33, 33a, 33b), wherein the first computation unit (32, 32a, 32b) is different from the second computation unit (33, 33a, 33b), wherein the first computation is a logical computation and the second computation is a floating point computation, or the second computation is a logical computation and the first computation is a floating point computation, wherein in a case that the first computation is the logical computation and the second computation is the floating point computation, the first computation unit (32, 32a, 32b) is configured to perform the logical computation and the second computation unit (33, 33a, 33b) is configured to perform the floating point computation, thus emulating the logical computation, and in a case that the second computation is the logical computation and the first computation is the floating point computation, the first computation unit (32, 32a, 32b) is configured to perform the floating point computation and the second computation unit (33, 33a, 33b) is configured to perform an integer computation by emulation. a first computation unit (32, 32a, 32b) configured to perform a first computation on a detected value that is detected from a subject to be controlled, thus obtaining a first result value; a second computation unit (33, 33a, 33b) configured to perform a second computation on the detected value, thus obtaining a second result value, and determine whether the first result value is equal to the second result value; an output control unit configured to output the first result value in a case that the second computation unit (33, 33a, 33b) determines that the first result value is equal to the second result value, the output control unit being configured not to output the first result value in a case that the second computation unit (33, 33a, 33b) determines that the first result value is not equal to the second result value; and a first central processing device including the first computation unit (32, 32a, 32b) and the second computation unit (33, 33a, 33b), wherein the first computation unit (32, 32a, 32b) is different from the second computation unit (33, 33a, 33b), wherein the first computation is a logical computation and the second computation is a floating point computation, or the second computation is a logical computation and the first computation is a floating point computation, wherein in a case that the first computation is the logical computation and the second computation is the floating point computation, the first computation unit (32, 32a, 32b) is configured to perform the logical computation and the second computation unit (33, 33a, 33b) is configured to perform the floating point computation, thus emulating the logical computation, and in a case that the second computation is the logical computation and the first computation is the floating point computation, the first computation unit (32, 32a, 32b) is configured to perform the floating point computation and the second computation unit (33, 33a, 33b) is configured to perform an integer computation by emulation.