A hard disk temperature monitoring device for monitoring a temperature of a hard disk in a computer system is provided. A hard disk stores an operating system. A basic input/output system (BIOS) has a setting configuration. When the setting configuration is a first setting value, operation of the hard disk is restored. When the setting configuration is a second setting value, the operation of the hard disk is stopped. A thermal sensor detects a temperature of the hard disk. A keyboard controller (KBC) is electrically connected to the thermal sensor via a data transmission channel for detecting the temperature of the hard disk in real time. If the KBC detects that the temperature of the hard disk rises to a first predetermined temperature, the setting configuration is set to the second setting value, and the BIOS stops the operation of the hard disk according to the second setting value.