There are included a normal model building unit that builds a normal model of another device on the basis of normal data of the other device; a degradation determination model building unit that builds a degradation determination model of the other device on the basis of the normal data and degradation data of the other device; a normal model rebuilding unit that builds a normal model of a target device on the basis of the normal model of the other device and normal data of the target device; a degradation determination model rebuilding unit that builds a degradation determination model of the target device on the basis of the degradation determination model of the other device and the normal model of the target device; and a degradation determining unit that determines degradation of the target device on the basis of operation data of the target device and the degradation determination model of the target device.