The functional anatomy of planning was investigated using a path-planning task, which required subjects to find a path to a goal that avoided obstacles and then move a cursor along the path to the goal by manipulating four switches. We analyzed event-related activation in response to four consecutive events during the path-planning task using fMRI. We classified activated cortical regions into four groups based on when each cortical region showed the most significant activation in response to behavioral events during the path-planning task. Our data suggested that each prefrontal and motor cortical area was involved in a different phase of path planning.