We examined the complexity effects of stimuli and tasks on temporal illusory conjunction in the Rapid Serial Visual Presentation (RSVP) tasks. Subjects were asked to report the partially defined target. We found that error patterns greatly depended on the visual complexity of stimuli. In the case of visually complex stimuli such as Kanji characters consisting of many strokes, pre-target intrusion errors were dominant. In contrast, post-target intrusion errors mainly occurred for visually simple stimuli such as alphabetic letters. Moreover, when target letters were not defined by a specific feature, pre-target intrusion errors were dominant for alphabetic letters. These results were discussed in view of the limited capacity of visual attention.