The invention concerns an apparatus (1) for producing three-dimensional objects (6) layer by layer using a powdery material which can be solidified by irradiating it with a beam (4) of charged particles, said apparatus (1) comprising means for successive application of powder layers to a work table, and a radiation gun (3) for delivering said beam (4) of charged particles, wherein the inventive apparatus (1) comprises a powder-lifting detection device (10, 10a, 10b, 10c, 10d, 10e) capable of generating a signal (S) upon detection of lifting of powdery material from the working area (5).