Dressing child for Japanese Wedding?

We have been invited to a Japanese wedding in October and want to know how to dress my 3 year old son. We are from Australia and the wedding is being held in Tokyo. I will wear a cocktail knee length black dress with a shawl and my husband a black suit, silver tie, white shirt.

You and your husband's clothing seems very nice and appropriate. Anything that suits you parents will be appropriate for your son. For example, a light color shirt with collar matched with darker color short pants with straps are typically seen.

Here are some photos just for reference. I Googled "boy's formal wear" in Japanese.
http://images.google.co.jp/images?hl=ja&rls=com.microsoft%3A*%3AIE-Sea...