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We analyse the properties of the X-ray emission from Seyfert 2 NGC 7172 whichare based on the 32 ks observational data from NuSTAR in 2014. This sourceshowed a constant Compton-thin obscuration $N_{H}\approx 8\cdot 10^{22}cm^{-2}$, which is similar to that observed by XMM-Newton, Suzaku, ASCA andBeppoSAX over past 30 years. We revealed the presence of a moderate reflectioncomponent with <R>~0.44 and a narrow FeK{\alpha} line with $67^{+13}_{-14}$ eV.The applied numerical models of torus confirmed the Compton-thin type of theSeyfert nucleus and allowed us to obtain an estimate of the torus opening angle${\Theta}_{t}\sim59\deg$ and inclination ${\Theta}_{i}\sim61\deg$. Using theobservation data of previous observation, we demonstrate also the long-termvariability of intrinsic luminosity $L_{intr}$(2-10 keV) almost by order and EW$FeK_{\alpha}$ by factor $\sim4$ on a timescale of $\sim12$ years, thatcoincides to the distance of $d\sim$3.7 pc between central source andreprocessing medium. Such changes of intrinsic luminosity without changes in$N_{H}$ value indicate the variability of a central source. In the same timethe spectral analysis results with the presence of the lag between variabilityof intrinsic luminosity $L_{intr}$(2-10 keV) and EW $FeK_{\alpha}$, as well asa behaviour of intensity $I_{FeK_{\alpha}}$ of the line are in agreement withthe scenario, where observed $FeK_{\alpha}$ line is generated in a distantgas-dust torus.

The obscured active nucleus of NGC 7172 as seen by NuSTAR