The name Betto-ji Temple arose from the betto (also known as shaso) who served these temples and conducted Shinto shrine rituals according to Buddhist practices such as the reciting of sutras in front of Shinto kami.
神前読経など神社の祭祀を仏式で行う者を別当（社僧ともいう）と呼んだことから、別当の居る寺を別当寺と言った。