To provide a safety cutter knife with which cutting work is enabled while covering the top end part of blade body.

Concerning the configuration of this safety cutter knife, the top end part of blade body 3 is covered by sliding a divided storage case 2 from a main body 1 of storage case. Besides, concerning the other side of safety cutter knife, one part of the main body 7 of storage case is cut away, one part of blade body 8 is exposed without exposing the top end part of blade body 8, and a divided storage case 6 is provided.