We present the first CDF measurement of the top quark's charge using its decay products based on close to 1 fb−1 of data. The Standard Model(SM) predicts the top charge to be + 2 / 3 but an alternative theory introduces an exotic quark of charge − 4 / 3 . We classify events as top like or exotic like depending on the the charge of the b jet and the associated W boson. We determine the charge of the b jet using the jet charge algorithm. We find the p-value under the SM hypothesis to be 0.35. Our p-value is consistent with the SM, and excludes the exotic quark hypothesis with 81% confidence, for which we have chosen a priori that the probability of incorrectly rejecting the SM would be 1%.