Disclosed is an automatic rebooting machine for a personal computer (PC) with a monitoring unit. A communication interface module is connected with a communication chip module. The communication chip module is connected with a +5 V power supply by connecting step-down filter capacitors and resistors in series and in parallel. Another two ports of the communication interface module are connected with two of ports of an MCU (micro control unit) chip module. The MCU chip module is connected with a +5 V power supply module, an external clock oscillator module and an MCU chip respectively. A rebooting switch is connected with an indicator light of a switch power supply. The rebooting switch is connected with a relay, a data indicator light is connected with the MCU chip module, a rebooting control output end of the rebooting indicator light is connected with the relay, and the other end of the relay is connected with a PC power supply part through control lines. A communication port is connected with a data port of the PC, and a power supply port is connected with 220V alternating current through an adapter. When the PC crashes and needs to be rebooted, the relay is controlled by the rebooting machine to reboot the PC, and the rebooting indicator light flickers to indicate.