NOx sensing properties of $Ba_2WO_5$ were investigated by varying the sintering temperature in an effort to study the effects of the neck-width on gas sensitivity. $Ba_2WO_5$ sintered at $800^{circ}C$, which exhibits neck-controlled conduction provides highest sensitivity of 47 and 29 at $500^{circ}C$ to NO and $NO_2$, respectively. The samples sintered beyond $800^{circ}C$ show sintering temperature-independent gas sensitivity. This may be because the grain boundary control is dominant at lower sintering temperatures and open neck control is dominant at higher sintering temperatures than $800{circ}C$. The NOx sensing mechanism of $Ba_2WO_5$ was briefly discussed.