This state monitoring device configured to monitor a current state of a vehicle includes: a storage configured to have stored therein a load index which is an index indicating an accumulation degree of a load having occurred in the vehicle; and a calculation unit configured to receive detection values of a plurality of sensors mounted on the vehicle, and configured to perform a predetermined calculation. The calculation unit includes: a status specification section configured to, by using the detection values of the plurality of sensors, specify, out of a plurality of status categories determined in advance and each indicating a status of use regarding running of the vehicle, one or more of the status categories; and an index update section configured to, on the basis of each specified status category, update the load index stored in the storage.