A portable terminal for reducing current consumption, the portable terminal comprising: a controller configured to: upon generation of a task in the portable terminal at a minimum clock rate of the controller, determine a load of the controller; if the load is equal to or higher than a predetermined value, transition a clock rate of the controller from the minimum clock rate to a specified clock rate that is higher than the minimum clock rate and less than a maximum clock rate; determine a load of the controller at the specified clock rate; if the load of the controller at the specified clock rate is equal to or higher than a first threshold value, determine that the load state of the controller at the specified clock rate corresponds to a first load state; if it is determined (S203, S204) that the load state of the controller at the specified clock rate corresponds to the first load state, increase the clock rate from the specified clock rate to the maximum clock rate; if the load of the controller at the specified clock rate is lower than the first threshold value and equal to or higher than a second threshold value, determine that the load state of the controller at the specified clock rate corresponds to a second load state; if it is determined (S203, S206) that the load state of the controller at the specified clock rate corresponds to the second load state, increase the clock rate from the specified clock rate by one-level in the second load state; if the load of the controller at the specified clock rate is lower than the second threshold value and equal to or higher than a third threshold value, determine that the load state of the controller at the specified clock rate corresponds to a third load state; if it is determined (S203, S208) that the load state of the controller at the specified clock rate corresponds to the third load state, maintain the clock rate in the third load state; if the load of the controller at the specified clock rate is lower than the third threshold value, determine that the load state of the controller at the specified clock rate corresponds to a fourth load state; if it is determined (S203, S210) that the load state of the controller at the specified clock rate corresponds to the fourth load state, decrease the clock rate from the specified clock rate by one level; after changing the clock rate, process the generated task at the changed clock level; and upon completion of the task, decrease the clock level at which the task has been processed. upon generation of a task in the portable terminal at a minimum clock rate of the controller, determine a load of the controller; if the load is equal to or higher than a predetermined value, transition a clock rate of the controller from the minimum clock rate to a specified clock rate that is higher than the minimum clock rate and less than a maximum clock rate; determine a load of the controller at the specified clock rate; if the load of the controller at the specified clock rate is equal to or higher than a first threshold value, determine that the load state of the controller at the specified clock rate corresponds to a first load state; if it is determined (S203, S204) that the load state of the controller at the specified clock rate corresponds to the first load state, increase the clock rate from the specified clock rate to the maximum clock rate; if the load of the controller at the specified clock rate is lower than the first threshold value and equal to or higher than a second threshold value, determine that the load state of the controller at the specified clock rate corresponds to a second load state; if it is determined (S203, S206) that the load state of the controller at the specified clock rate corresponds to the second load state, increase the clock rate from the specified clock rate by one-level in the second load state; if the load of the controller at the specified clock rate is lower than the second threshold value and equal to or higher than a third threshold value, determine that the load state of the controller at the specified clock rate corresponds to a third load state; if it is determined (S203, S208) that the load state of the controller at the specified clock rate corresponds to the third load state, maintain the clock rate in the third load state; if the load of the controller at the specified clock rate is lower than the third threshold value, determine that the load state of the controller at the specified clock rate corresponds to a fourth load state; if it is determined (S203, S210) that the load state of the controller at the specified clock rate corresponds to the fourth load state, decrease the clock rate from the specified clock rate by one level; after changing the clock rate, process the generated task at the changed clock level; and upon completion of the task, decrease the clock level at which the task has been processed.