The research was conducted to evaluate supplemental effect of purple sweet potato extract (PSPE) on protein intake, ileum protein digestibility and meat protein mass. The experiment was assigned in a randomized complete design with 2×3 factorial scheme, 6 treatments and 4 replications. The first factor was cage density (normal density/D1 = 8 birds/m2 and high density/D2 = 16 birds/m2), and the second factor was the extract levels of purple sweet potato (A0 = control diet, A1 = diet containing 25 ml PSPE/kg feed and A2 = diet containing 50 ml PSPE/kg feed). Birds were kept in a brooder cage for 14 days and then transferred to colony cages (1×1 m) until the age of 35 days. When measurement of protein digestibility the birds were moved to individual battery cage on day 35. The experimental feed contained 21% crude protein and metabolizable energy of 3000 kcal/kg. The results showed that the extract of purple sweet potato and cage density did not show significant (P>0.05) interaction. The supplementation of purple sweet potato extract significantly (P<0.05) affected protein intake, protein digestibility and meat protein mass, while the cage density affected only the protein digestibility.