A reverse bias voltage adjuster is provided. The reverse bias voltage adjuster includes an operating voltage generating circuit and a voltage adjusting circuit. The operating voltage generating circuit generates an operating voltage according to a burnin-test signal, a power start signal, and a reverse bias enable signal. In a normal operation mode, the operating voltage is a first voltage value, and in a burnin-test mode, the operating voltage is a second voltage value, wherein the second voltage value is less than the first voltage value. The voltage adjusting circuit is provided with a switch, and in an initial time interval in the burnin-test mode, the voltage adjusting circuit adjusts voltage value of the reverse bias by turning on the switch.