This surgical instrument is provided with: an insertion section； a grasping member provided at a distal end portion of the insertion section and formed in a curved shape； a guide section formed along the curved shape and disposed at the grasping member； a first guided section having a disc shape； a second guided section provided at a proximal side of the guide section closer than the first guided section and having a disc shape； a base to which the first guided member and the second guided member are attached； a blade section fixed to the base and protrudes from the grasping member, the blade section being movably along the curved shape of the grasping member by sliding the first guided member and the second guided member along the guide section.
