In this report, a new batch integration process of silicon nanowire (SiNW) to a MEMS device structure has been proposed and was demonstrated. To overcome the difficulty in integrating nano-scale components to micro-scale devices and controls the diameter of a free-standing SiNW, this process consists of Bosch process, isotropic silicon etching and thermal oxidation which enables to fabricate, assemble and fix a free-standing SiNW without complicated nanowire handling operations. The process was applied to tensile testing device using silicon-on-insulator wafer to evaluate mechanical properties of the nanowire. Consequently, a free-standing SiNW of 223 nm wide and 5 μm long with smooth surface was successfully integrated to the 5-μm-thick device without any damages.