- This film is adapted from the 1986 book Howl's Moving Castle by British fantasy writer Diana Wayne Jones.
- The chance to adapt to animation came in 1999. Hayao Miyazaki received the Japanese version of the novel "Magic Castle" from Tokuma Shoten(a publishing company in Japan).
- In 2002, Miyazaki went to Colmar and Riquewihr in Alsace, France, to study the architecture and the surroundings for the film's setting.
- The total number of paintings in the works is 148,786.
- On the second day of the release, the audience was 1.1 million, the highest opening launch ever for a Japanese movie. With 15 million audiences in six months.
