A distribution system for distributing an application from a distribution server to a user terminal through a communication network, in which the distribution server optimizes a program code of the application in question based on execution data indicative of execution conditions of the application in question at the user terminal in question to distribute the obtained application to the user terminal and the user terminal includes a unit for obtaining a program code and execution data of an application from the distribution server to execute the obtained program code based on execution conditions of the application in question indicated in the execution data, and a unit for obtaining execution data of an application being executed to transmit the execution data to the distribution server.