A system, method and computer program for generating a sequence diagram that specifies processing among modules included in source code. First, a source code is acquired and then analyzed to generate a log acquisition code for acquiring an execution log. Then, a program including the generated log acquisition code is executed to acquire execution log information on the execution of the program. On the basis of the acquired execution log information, automaton information on states and transitions among the states is extracted, and then the extracted automaton information is converted into sequence diagram component information on components constituting a sequence diagram. Thereafter, a sequence diagram is generated based on the converted sequence diagram component information.