Abstract: A semiconductor device connectable to a host includes a plurality of semiconductor memory units, which includes first and second memory units, a temperature sensing unit, and a controller. The temperature sensing unit is configured to detect temperatures of the plurality of semiconductor memory units, and includes a first sensor positioned to detect a temperature of the first memory unit, as a first temperature, and a second sensor positioned to detect a temperature of the second memory unit, as a second temperature. The controller is configured to receive a command to access the first memory unit from the host, and in response to the command, access the second memory unit and not the first memory unit, when the first temperature is higher than a first predetermined value and the second temperature is lower than a second predetermined value.