Recently, many cases of using biodegradable scaffolds for tissue engineering have been investigated to substitute for prosthetic vascular grafts. We have fabricated a tubular double-layered scaffold using a gel spinning technique from an elastic biodegradable polymer, poly(L-lactide-co-ε-caprolactone)(PLCL, 50:50). The double-layered scaffold was composed of outer fibrous network and inner porous membrane. In this study, we examined the effect of unintended pores formed in inner membrane on the mechanical properties of the scaffolds. A conditioning mixer was used to remove unintended pores which result in heterogeneous pore distribution in inner membrane. In particular, it was proved form SEM images that unintended large pores were almost completely removed through defoaming and mixing processes utilizing conditioning mixer. There was no statistical meaning in the differences of tensile properties, suture retention, and burst strength between scaffolds fabricated with mixer and those fabricated without mixer. However, scaffolds fabricated with mixer were significantly improved in an aspect of blood leakage showing the increase of leakage pressure and the even dilatation of scaffolds as compared with those fabricated without mixer. Taken together, unintended pore is a factor to be considered for vascular scaffold fabrication and homogenous pore distribution in the porous inner membrane of double-layered scaffold primarily exerts an influence on the blood leakage of the scaffold.