Disclosed are a driver state monitoring method and apparatus. The driver state monitoring apparatus includes a driver state sensing unit to sense a driver state； a vehicle state sensing unit to sense a vehicle state, an ambient environment state sensing unit to sense an ambient environment state of the vehicle, a warning unit to warn a driver of a driver carelessness state, and a controller to assign a weighted value to the driver state sensed through the driver state sensing unit and the vehicle state sensed through the vehicle state sensing unit, respectively, based on an ambient environment state sensed through the ambient environment state sensing unit, calculate a driver carelessness level by applying the assigned respective weighted values, determine whether the driver is in a carelessness state or a normal state based on the calculated driver carelessness level, and warn the driver through the warning unit if the driver is in the carelessness state.
