To provide a tool fitting position adjusting device and a tool fitting position adjusting method, simple in constitution and easily adjusting the fitting position of a tool to a tool holder.

In this tool fitting position adjusting device, a tool holder 101 is retained in a tool holder retaining means 10, a tool 115 whose shank part 116 is inserted in a tool fitting hole 105 of the tool holder 101 to freely move forward and backward is clamped by a tool movement retaining means 30, and the tip 117a of a knife edge is guided to a tool position regulating part 25 of a knife edge tip position measuring means 20 and abutted on it. The fitting position of the tool 115 to the tool holder 101 is regulated by abutting of the knife edge tip 117a against the tool position regulating part 25, whereby the fitting position of the tool 115 to the tool holder 101 is easily adjusted.