"Tomadoi Nagara" (とまどいながら, While Lost) is the tenth single of the Japanese boy band Arashi. The single was released in 2003 in two editions: a regular edition and a limited edition with a deluxe cover art. Both editions contain the same tracks. The limited edition includes a hidden track, the continuation of the group's Secret Talk from "Pikanchi".
"Tomadoi Nagara" was used as the theme song for the drama Yoiko no Mikata (よい子の味方, Ally of Good Children) starring Arashi member Sho Sakurai in his first lead role.