Provided is a magnetic sensor device. In order to set a detection voltage level, a detection voltage setting circuit formed by a tapping resistor needs to be set and a circuit structure is complex. Besides, Hall elements and the power system of the detection voltage setting circuit are separated, thus test voltage level error can generate by the influence. In addition, in order to remove each offset element, three signal processing periods including two sampling stages and one comparing stage are needed. For solving means, four switches switch and connect each terminal of the Hall elements and one end with the other end of a variable resistor connected with a GND. Accordingly, a small scale circuit can be utilized to set randomly a detection voltage level of magnetic intensity; the detection voltage is only determined by resistance and is not influenced by power voltage or manufacturing deviation. In the structure, signal processing is simplified and high sped is realized.