  The hydrogen cyanide (HCN) molecule in the planetary atmosphere is key to the
formation of building blocks of life. We present the spectroscopic detection of
the rotational molecular line of nitrile species hydrogen cyanide (HCN) in the
atmosphere of Saturn using the archival data of the Atacama Large
Millimeter/Submillimeter Array (ALMA) in band 7 observation. The strong
rotational emission line of HCN is detected at frequency $\nu$ = 354.505 GHz
(>4$\sigma$ statistical significance). We also detect the rotational emission
line of carbon monoxide (CO) at frequency $\nu$ = 345.795 GHz. The statistical
column density of hydrogen cyanide and carbon monoxide emission line is
N(HCN)$\sim$2.42$\times$10$^{16}$ cm$^{-2}$ and
N(CO)$\sim$5.82$\times$10$^{17}$ cm$^{-2}$. The abundance of HCN and CO in the
atmosphere of Saturn relative to the H$_{2}$ is estimated to be
f(HCN)$\sim$1.02$\times$10$^{-9}$ and f(CO)$\sim$2.42$\times$10$^{-8}$. We
discussed possible chemical pathways to the formation of the detected nitrile
gas HCN in the atmosphere of Saturn.
