Large domains of monolayered transition-metal dichalcogenides (TMDCs) have emerged as exciting material systems because of their potential to provide a platform for ultrathin circuits and optoelectronics systems. Here we report ambient pressure chemical vapor deposition (CVD) growth of large scale MoSe2 film for terahertz (THz) applications. Arrays of 100×60 µm MoSe2rectangle layers were etched out and field effect transistors (FETs) were fabricated on these arrays. The device exhibits current on/off ratio of ∼104. The THz photoresponse of the devices was studied and demonstrated the THz responsivity of ~38 mV/W, suggesting that TMDCs can be promising materials for long wavelength optoelectronics applications.