The present invention realizes a micromechanical sensor device with a movable gate and a corresponding production method. The micromechanical sensor device with the movable gate includes a field effect transistor having a drain region (3), a source region (4), a channel region (7) arranged between the field effect transistor and the source region and including a first doping type, and a movable gate (1). The movable gate is separated from the channel region (7) by an interspace (Z). The drain region (3), the source region (4), and the channel region (7) are arranged in a substrate (2). An oxide region (8; 8a; 8b) is provided in the substrate (2) at least at longitudinal sides (S1, S2) of the channel region (7).