Tsuchigumo soshi is a fascinating otogizoshi story of a haunted house full of strange creatures that extols the prowess of Minamoto no Raiko (or Yorimitsu, 948-1021), recounting how he vanquished a gigantic earth spider. Although spiders appear in ancient Japanese texts, this picture scroll is the oldest extant work in which a spider is portrayed as a supernatural creature. I speculate that the spider's transformation to an evil, uncanny creature is due to its association with an oni (demon, ogre). During the early modern period, the earth spider was notorious in literature and theatrical performance as a shape-shifting killer. The Nihon shoki and the "Swords chapter" of Heike monogatari are widely recognized sources for an influential Noh play, Tsuchigumo, which is rightfully cited as a work that greatly influenced later tsuchigumo literature and performance. I believe Tsuchigumo soshi should be regarded as a source for the Noh play and for the emergence of an image of tsuchigumo as a killer shape-shifter. A complete translation of Tsuchigumo soshi accompanies this article. KEYWORDS: Earth Spider--oni--picture scroll--otogizoshi--Noh