The present invention relates to a polypeptide derived from CAP1 and a pharmaceutical composition comprising the same as an effective ingredient and, more particularly, to a peptide including the amino acid sequence of SEQ ID NO: 1, any 0 to 20 amino acid residues added to the N terminus thereof, and any 0 to 75 amino acid residues added to the C terminus thereof, and a pharmaceutical composition comprising the peptide as an effective ingredient for the prevention and alleviation of inflammatory diseases, the inhibition of cancer and cancer metastasis, the prevention and alleviation of diabetes, the prevention and alleviation of arteriosclerosis or cardiovascular diseases, and the prevention and alleviation of heart failure. Exhibiting the effect of suppressing the binding of resistin to CAP1 and inhibiting NF-κB activity, the method of the present invention can be useful for treating inflammatory diseases, cancer, diabetes, arteriosclerosis, cardiovascular diseases, and heart failure which are caused by the activation of resistin and NF-κB.