This study scopes in the application of Lorentz force for the magnetic field detection using micromachined device. The device is designed and simulated using CoventorWare simulation software. The design is based on CMOS technology and surface micromachining. The response of the device in external magnetic field is discussed in two situations: static and dynamic. It was observed in static case a displacement of 47.4 nm, while for the dynamic case it was 0.237 μm in the center of beam. The device has a resonant frequency of 66.64 MHz and a quality factor 6 with important features such as small device size. Earth's magnetic field is used as source of actuation and sensor response towards the variation in external magnetic field is 99.9 linear with sensitivity of 0.05 μA/μT. © 2010 IEEE.