This paper presents a Lorentz force magnetometer with a MEMS resonator structure as a sensor. Magnetometer composed of a resonator and a grill structure. The grill structure reduces the heat generation due to the current required to generate the Lorentz force. The proposed sensor is produced with standard SOI micromachining processes with device layer thickness of 35 mu m. The natural frequency of resonator is around 83 kHz, Q-factor of 1870 at around 40 mTorr ambient pressure. Tests are done for 1.12 mT magnetic field in the direction of normal to the resonator plane supplied by a Maxwell coil. The scale factor of the magnetometer is measured to be 5400 Hz/T. Comparing with similar resonators and given that the Lorentz force is linearly proportional to magnetic field with constant current and wire length, the resolution and bias instability are calculated to be 4.2 mu T/Hz(1/2) and 280 nT, respectively.