An apparatus (1) for additive manufacturing of three-dimensional objects (2) by successive, selective layer-by-layer exposure and thus successive, selective layer-by-layer solidification of construction material layers of a construction material (3) that can be solidified by means of laser radiation in a process chamber (10) of the apparatus, comprising an exposure device (5) provided for generating laser radiation for selective exposure and thus selective solidification of respective construction material layers, and a detection device (11) provided for detecting the entering of laser radiation into a process chamber limiting element at least partially limiting the process chamber (10) and/or for detecting the penetration of laser radiation through a process chamber limiting element at least partially limiting the process chamber (10).