A warmer device includes a protection device, a rechargeable warmer bag and a monitoring device. The rechargeable warmer bag includes a bag, a heating unit, a charging unit, and a monitoring unit for protecting the rechargeable warmer bag. When the rechargeable warmer bag is being charged in the cavity of the protection device, the rechargeable warmer bag is monitored by the monitoring device. When the rechargeable warmer bag is heated to be over expanded, the monitoring device disconnects the external circuit to protect the rechargeable warmer bag from being broken or explosion. When the rechargeable warmer bag is being used, the rechargeable warmer bag and the monitoring device are separated.