The present study investigated the effects of task complexity and pre-task instruction on oral production by intermediate learners of Japanese. Previous studies have reported that task complexity affects L2 learners· performance. The relationship between increased complexity and aspects of oral production such as complexity, accuracy, and fluency of speech. has not been fully investigated. Further, some studies have found that providing pre-task instruction enhances the quality of production. However, its effects vary, depending on the specificity and focus of instruction, and few studies have investigated how pre-task instruction affects learners of languages other than English. Accordingly, the present study examined the effects of pre-task instruction and task complexity in intermediate learners of Japanese. Fourteen Chinese learners of Japanese enrolled in four private language schools in Japan were shown two sets of cartoons, one representing a simple story and the other a complex one. They were subsequently asked to relate the stories. In the first story-telling task, the subjects were given ten minutes to plan the task without any guidance. In the second task, they received instruction on how to plan the task in that time. Their oral production was recorded and analyzed in terms of complexity, accuracy, and fluency. The results showed that the pre-task instruction negatively affected complexity, accuracy, and fluency, although one of the two measures of complexity was not affected by the instruction. Also, increased task complexity did not result in improved oral production. These results suggest that the task employed in the present study may have been too difficult for the learners to receive any advantage through instruction.