A plate-like cutting tool produced at a low cost and having less strain is provided. A planer knife basically includes a base 12 formed of a steel, and cutting blades 14, 14 to be laser-welded along both lengthwise end edge portions 12a, 12b in a lengthwise direction of the base 12. A recess 22 engageable with a to-be-engaged portion 24a of a base supporting section 24 of a fixing jig 20 is provided at a back side 18 of the base 12. In the process of manufacturing the planer knife, with the base 12 engaged with the to-be-engaged portion 24a, the base 12 is fixed onto the base supporting section 22, and is held and fixed in a pressed state by a first base fixing tool 36. The cutting blade 14 is fixed in abutment on the lengthwise end edge portion 12a via a cutting blade fixing tool 46. Then, mainly the base 12 is laser-welded at a contact portion between the lengthwise end edge portion 12a and the cutting blade 14, thereby attaching the cutting blade 14 to the base 12.