For 2014 manga, please refer Shirobako: Kaminoyama High School Animation Club.
A SHIROBAKO manga adaptation is now in serialization from February 28, 2020. The manga released on a manga website called Manga Kingdom(まんが王国). The manga is written by Rina Fujita (藤田里奈 Fujita Rina) and illustrated by Yatomi (やとみ Yatomi).
The manga is a retelling of the anime.