The present invention has an display section for displaying an operation state of a program to a user in a time series manner based on program execution history information, an input section for allowing the user to designate a portion of a defect in the displayed operation sate, and an operation analysis section for analyzing a cause of the defect from the portion of the defect pointed out from the user by the input section and from the operation state of the program, and for specifying a solution for solving the cause of the defect. The operation analysis section regenerates the operation state on which the specified solution is reflected, and the display section displays the cause of the defect, the solution and the regenerated operation state to the user.