The prefrontal cortex has been known to participate in working memory processes. Tonic sustained activation observed during the delay period (delay-period activity) has been considered as a neural correlate of the mechanism for active maintenance of information. Neurophysiological studies revealed that delay-period activity represents retrospective information (e.g., sensory events) as well as prospective information (e.g., forthcoming motor information). This suggests that delay-period activity participates in decision processes regarding motor performances based on the sensory information. To examine how delay-period activity participates in the decision of a motor behavior, we analyzed prefrontal activity while monkeys performed two tasks: ODR and S-ODR tasks. In the ODR task, monkeys were required to make a memory-guided saccade to the cue location after a 3-s delay. In the S-ODR task, four identical visual cues were presented simultaneously during the cue period and monkeys were required to make a saccade in any one direction after the delay. Delay-period activity was observed in both tasks in the same neuron with similar directional preferences. Neurons with delay-period activity were classified into several groups based on the temporal pattern of the activity itself and of the strength of the directional selectivity. Among these, neurons with an increasing type of delay-period activity with persistent directional selectivity throughout the delay period in the ODR task also showed directional delay-period activity in the S-ODR task. These results indicate that an increasing type of delay-period activity, which is thought to represent motor information, plays an important role in generating and enhancing directional bias in the S-ODR task and therefore contributes significantly to the decision process of the saccade direction in the S-ODR task.