1 EXHIBIT 23(a) CONSENT OF ERNST AND YOUNG, LLP, INDEPENDENT AUDITORS We consent to the incorporation by reference in the registration statement on Form S-8 of Comerica Incorporated, pertaining to the registration of 3,000,000 shares of common stock with respect to the Comerica Incorporated 1997 Long-Term Incentive Plan, of our report dated January 22, 1997, with respect to the consolidated financial statements of Comerica Incorporated, incorporated by reference in the Annual Report (Form 10-K) for the year ended December 31, 1996 filed with the Securities and Exchange Commission. March 31, 1997 E-3