The purpose of this research is to detect the atomic spectrum of cesium using laserinduced breakdown spectroscopy (LIBS). In this study, pollucite ((Cs,Na)(AlSi2)O6.nH2O) was used as a test sample for the LIBS measurement. LIBS is a useful tool for the determination of the elemental composition of various materials and it does not require any preprocessing step. The Nd:YAG laser was operated at 1064 nm to generate a 50-mJ Q-switched pulse with a width of 8 ns (full width at half maximum, FWHM). The breakdown emissions were dispersed by a grating with a groove density of 1200 lines/mm and the resulting electrical signal was recorded using a streak camera. The plasma intensity was optimized with respect to the background. Spectral measurements were carried out after an appropriate delay time to allow for the decay of the continuum radiation. In the experiments, 100 laser shots were used to record data for each spectrum in ambient air. The results of the experiments showed that the atomic signals corresponding to pollucite were obtained easily by LIBS measurements. Thus, spectrum peaks due to cesium, sodium, aluminum, and silicon are observed. In particular, the characteristics of the cesium spectrum play an important role in establishing the LIBS system for environmental monitoring, which may be used to detect radioactive elements emitted from nuclear plants.