To provide a temperature management device in bed by which comfortable sleep can be attained depending on the sleep depth.

In this device, heartbeat strength signal is calculated from heartbeat signal detected using heartbeat signal detection means, and heartbeat strength dispersion value of data in fixed time for the heartbeat strength signaling is calculated. The device is equipped with a sleep depth judging means 2 for judging the sleep depth from heartbeat strength dispersion value, a bed temperature measurement means 3 for measuring the temperature in bed, bedclothes 4 with a built-in temperature control means, and the temperature control means 5 for controlling the temperature in the bed depending on the sleep depth judged by the sleep depth judging means. The temperature control means for controlling the temperature in bed includes an electric blanket 4, a temperature control mat containing thermoregulated fluid, an air sheet supplying thermoregulated air into the bed, and an indoor temperature control device which regulates the indoor temperature of the room.