A MEMS resonator is equipped with a substrate, a moving structure suspended above the substrate in a horizontal plane formed by first and second axes, having first and second arms, parallel to one another and extending along the second axis, coupled at their respective ends by first and second transverse joining elements, forming an internal window. A first electrode structure is positioned outside the window and capacitively coupled to the moving structure. A second electrode structure is positioned inside the window. One of the first and second electrode structures causes an oscillatory movement of the flexing arms in opposite directions along the first horizontal axis at a resonance frequency, and the other electrode structure has a function of detecting the oscillation. A suspension structure has a suspension arm in the window. An attachment arrangement is coupled to the suspension element centrally in the window, near the second electrode structure.