An application management system for managing a plurality of applications installed in an image processing device, comprising: start instruction reception means for receiving an instruction to start execution of one or more of said plurality of applications; application execution means for executing said one or more applications; screen output means; and determination means (10, 12), wherein the application management system is characterized by the determination means (10, 12) being configured to, in a case where the start instruction reception means receives a first application execution start instruction to start execution of a first application among said plurality of applications in a case that a second application among said plurality of applications has already been executed, determine whether one of the first and second applications has a predetermined function (S1202, S1305) and the other one of the first and second applications is compatible with the predetermined function (S1206, S1306) of said one of the first and second applications, and the screen output means being configured to output a warning screen about start of execution of the first application in accordance with a determination that one of the first and second applications has the predetermined function and other one of the first and second application is non-compatible with the predetermined function, wherein each of said plurality of applications installed in the image processing device has attribute information, and the determination means performs the determination by referring to the attribute information of the first application and the attribute information of the second application which has been executed by the application execution means, and wherein the determination means reads out requirement information indicating a condition of an application which can be concurrently executed with the first application from the attribute information on the first application, reads out compatible information indicating compatibility to the second application, and determines that the application is an incompatible application if the requirement information and the compatible information are not matched. start instruction reception means for receiving an instruction to start execution of one or more of said plurality of applications; application execution means for executing said one or more applications; screen output means; and determination means (10, 12), wherein the application management system is characterized by the determination means (10, 12) being configured to, in a case where the start instruction reception means receives a first application execution start instruction to start execution of a first application among said plurality of applications in a case that a second application among said plurality of applications has already been executed, determine whether one of the first and second applications has a predetermined function (S1202, S1305) and the other one of the first and second applications is compatible with the predetermined function (S1206, S1306) of said one of the first and second applications, and the screen output means being configured to output a warning screen about start of execution of the first application in accordance with a determination that one of the first and second applications has the predetermined function and other one of the first and second application is non-compatible with the predetermined function, wherein each of said plurality of applications installed in the image processing device has attribute information, and the determination means performs the determination by referring to the attribute information of the first application and the attribute information of the second application which has been executed by the application execution means, and wherein the determination means reads out requirement information indicating a condition of an application which can be concurrently executed with the first application from the attribute information on the first application, reads out compatible information indicating compatibility to the second application, and determines that the application is an incompatible application if the requirement information and the compatible information are not matched.