There is provided a bulk bias voltage VBB level detector in a semiconductor memory device capable of improving tWR fail generated at a low temperature by compensating a temperature variance. The VBB level detector includes A bulk bias voltage level detector in a semiconductor memory device, comprising: a voltage divider for generating detection voltage based on an inputted bulk voltage; and a CMOS circuit for generating a output signal having predetermined logic value determined by the detection voltage wherein the voltage divider includes a first transistor having a gate coupled to a ground voltage and a second transistor having a gate coupled to an internal power voltage and a bulk coupled to the inputted bulk voltage.