A vehicle communication processor includes a communication control unit that receives digitally signed information from an external device, and a first control processing unit and a second control processing unit that process information received by the communication control unit. The communication control unit or the first control processing unit includes a sign verification section that performs an authenticity verification of a digital sign of the digitally signed information. The second control processing unit includes an execution preparation section and an execution determination section. The execution preparation section performs an execution preparation process on data of the digitally signed information in parallel to the authenticity verification on the digital sign. The execution determination section determines whether the data of the digitally signed information is to be executed in a case where the digital sign of the digitally signed information is verified as being authentic.