Portable terminal varying management of task group in time based on received execution request of task group and weak task group

According an aspect of the invention, a mobile terminal includes a task executing unit configured to execute a plurality of task groups and a management unit configured to manage to execute in a first order the task groups. If the task executing unit executes a first task group in foreground and if the management unit receives a first request executing a second task group different from the first task group, the management unit manages the first and the second task groups as one chain and executes the second task group in foreground. If the task executing unit executes the first task group in foreground and if the management unit receives a second request executing a third task group different from the first and second task groups, the management unit manages the first and third task groups as other chain and executes the third task group in foreground.