To generate a series for efficiently determining proper call relationships between tasks.

The task discrimination unit 1b of a series generating apparatus 1 identifies a task executed on a first device and tasks executed on a second device, on the basis of messages exchanged between those devices. A series grouping unit 1c refers to a storage unit which stores models defining call relationships which can be generated between the task executed on the first device and the tasks executed on the second device. The series grouping unit 1c generates a series of tasks from a callable sequence of tasks as an array of the tasks executed on the second device during the execution time of the task executed on the first device. The series grouping unit 1c generates, as a series of tasks, a sequence of tasks including a sequence of tasks that partially match the sequence of tasks defined as called tasks in the model using the task executed on the first device as a calling task, while excluding therefrom the tasks that cannot be the called tasks.