A novel design of micro-machined variable optical attenuator (VOA) with a packaged size as small as 25 × 10 × 7 mm³ is presented. Attenuation was introduced by a rotatable miniature silicon mirror,with its orientation finely adjusted through the balance between a pair of electromagnetic forces. The design is free of conventional spring restoring force for attenuation reset and therefore ensures a high stability. The realizing structure was fabricated by EDM micro-machining as well as laser spot welding. VOA prototypes exhibit a wide attenuation range of 40 dB with an insertion loss of 0.8 dB and backreflection of －50 dB. The measured result was compared with that of an FEA model using ANSYS software package and a good agreement was obtained. The VOA can be arrayed for effective signal balancing and device protection in WDM/DWDM network systems.