With an evaluation device, a sleep level of a person being measured is discriminated based on a signal input from a body motion sensor. With the evaluation device, when a go-to-bed button is operated at time T3, time T3 is stored as the go-to-bed time. When a good-night button is operated at time T4, discrimination of sleep level is started. Thereafter, when the good-night button again is operated at time T5, the discrimination of sleep level ends.