Detection and control of toxic gas molecules are becoming more and more indispensable. In this paper, the electronic properties of primary and adsorbed transition metal (TM) atoms (Mo, Ni, Pd, Ti and Zr) arsenene with the adsorption of toxic nitrogenous gas molecules (NH3, NO and NO2) by using first-principles methods. The calculated results show that the adsorption of transition metal atoms significantly enhances the interaction between gas molecules and the substrate. In particular, the arsenene with Ti or Zr adsorbed has the best adsorption energy and the most charge transfer from the substract to gas molecules. Most of the systems retain their semiconductor properties, expect for the Zr-Arsenene with nitric oxide adsorbed, which have unique metallic properties. Interestingly, the system with NO and NO2 adsorbing can induce the magnetism. At the same time, uniaxial strain can change the adsorption strength of the system, and adjust the NO2 sensing characteristics of arsenene. It is hoped that the arsenene with transition metal adsorbed is a potential candidate for the detection of nitrogen-containing toxic gas molecules.