[ $Co_{1-x}Fe_xSb_3$ ] skutterudites were synthesized by encapsulated induction melting and their thermoelectric properties were investigated. Single phase ${delta}-CoSb_3$ was successfully obtained by the subsequent heat treatment at 773 K for 24 hours in vacuum. However, ${delta}-CoSb_3$ was decomposed to FeSb2 and Sb when $x{leq}0.3$, which means that the solubility limit of Fe to Co is x<0.3. The positive signs of Seebeck coefficients for all Fe-doped specimens revealed that Fe atoms acted as p-type dopants by substituting Co atoms. Thermoelectric properties were remarkably enhanced by Fe doping and optimum composition was found to be $Co_{0.7}Fe_{0.3}Sb_3$ in this study.