Recently, a newly fabricated two-dimensional layer structured material so-called phosphorene is receiving great research interests due to its peculiar physical properties. So far, mostly electrical properties are explored because it has a direct band gap and its nonmagnetic behavior in pristine layer. In this report, we propose that the transition metal doped phosphorene layer can have dilute magnetic semiconductor properties. Here, we investigated the structural property, binding energy, and magnetic property by changing the TM impurity dopants in the substitutional site. Our results demonstrate that spin polarized semiconducting state is realized in phosphorene by substitutional doping of Ti, Cr, and Mn, while a half-metallic state is obtained by V and Fe doping. In particular, we suggest that the most promising dopants are Cr and Mn because the spin polarized state is achieved with a band gap larger than 0.5 eV. The magnetic interaction between two same types of TM atoms is also checked. Magnetic ground state was obtained with GGA and GGA+U approaches are quite consistent, except for Mn- and Fe-doped systems. These findings indicate that the TM-doped phosphorene can be used as a potential next-generation spintronics material.