Mobile payment system has many problems in real mobile payment networks because of the characteristics of mobile device and the security of mobile payment process. Specially, the previous suggested mobile payment protocol can not verify a trust of issuing bank. Therefore, this paper has analyzed the efficiency of a mobile payment with a delegating authority for an issuing bank to trust issuing bank. As a result, the mobile payment protocol with a delegating authority for a payment verification of an issuing bank has improved the time complexities for key computation and communication resilience.