Williams syndrome is known for uneven cognitive abilities. Visuospatial difficulties such as a failure in constructing objects are considered to be characteristic and may influence the copying of Japanese semantic characters, kanji. In contrast to previous investigations, which were done mainly cross-sectionally, this study focused on the developmental aspects of the symptoms, to get a better view of the mechanism. Developmental changes in visuospatial abilities (including copying two-dimensional figures, three-dimensional figures, and kanji) in four boys with Williams syndrome, ages 4 to 11 years, were longitudinally observed for 6-9 years. The Benton's three-dimensional block construction tests and the Yerkes test were also performed. Some of the results were compared with those of mental age-matched children. The observation revealed improvements in performance for copying two-dimensional figures, as well as for copying kanji, in the Williams syndrome participants; however, copying three-dimensional figures tended to remain difficult, especially if in a transparent view. Obtaining three-dimensional information using pictorial cues seemed to remain difficult for the Williams syndrome participants even at the later stage of study monitoring. This difficulty might be correlated with the core dysfunction of Williams syndrome.