Wasshoi Hyakuman Natsumatsuri (わっしょい百万夏祭り) is a matsuri in Kokura Kita-ku, Kitakyūshū, Fukuoka, Japan.

It is Kitakyūshū's largest festival, having been created to celebrate the 25th anniversary of the creation of the city.

When Kitakyushu celebrated the 10th anniversary of its creation as a municipality and ordinance-designated city in 1973, a Junior Chamber International corporation held an event called the "Kitakyushu Matsuri", and on the 25th anniversary, the current Wasshoi Hyakuman Matsuri was started.

The hyakuman odori (百万踊り), a yosakoi dance that originated in Kōchi has been performed every year since 2003.

Due to the participation of groups from around the city, it is possible to see many unique aspects of other festivals, such as floats from Wakamatsu-ku and Kurosaki or "light pyramids" from Tobata-ku.