A monitoring device is for the inner pressure distribution of building material in a building structure. The device may include planar sensing capacitors to be buried in contact with the building material, with each sensing capacitor including a pair of plates and a dielectric material layer therebetween adapted to undergo elastic deformation under pressure without deforming plastically. The device may also include a protection box to be buried in the building material, a dielectric material enclosed in the protection box, and connection terminals protruding from the protection box. Pairs of metal vias are buried in the dielectric material enclosed within the protection box, with each pair connecting the plates of a respective planar sensing capacitor to respective connection terminals.