The paper presents a method of structural monitoring using measurement of vertical displacements realized optically by horizontally directed laser beam. A measuring device with an integrated rangefinder and inclinometer sensor was developed. Inclinometer sensor are used to correct measurement results of the rangefinder in order to eliminate errors resulting from spatial position changes of the laser beam. Such a solution was adopted as an alternative to a more complex and demanding method, which is the stabilization of the laser beam orientation. The proposed inclinometric correction method allows in a simple and clear way to eliminate a serious problem of the displacement measurement method with a perpendicularly directed laser beam, which is inevitable in practice the lack of permanent stability of the measuring device position. The developed measuring device is wireless, both in terms of power supply and communication with other elements of the monitoring system. In order to verify the correctness of measurements carried out by the developed device, on site tests were carried out in two industrial-warehouse buildings with functioning monitoring systems using other measurement methods, earlier verified. The tests confirmed compliance with the indications of the existing system at a level completely sufficient for structural monitoring system purposes. The conducted research show that the proposed method of displacements measurement with inclinometric correction of errors, provides accurate and reliable results, allowing also to obtain additional information about the behaviour of the structure in the place of installation of the measuring device.