PROBLEM TO BE SOLVED: To realize that: wear in a wall part facing to tool tip side of an insert attachment base on which a wiper insert is attached may be prevented and precision in cutting machining is maintained in high quality and stably while a plurality of insert attachment bases have a common configuration, but not discriminated with a standard machining insert and a wiper insert.SOLUTION: A device comprises: a plate-like insert main body 41; a front and back surfaces 42 of the insert main body 41; an outer peripheral surface 43 connecting peripheral edges of the front and back surfaces 42 each other; a cutting blade 44 formed on a crossing ridge line of at least front surface 42 of the front and back surfaces 42 and the outer peripheral surface 43. The cutting blade 44 comprises a flat drag 44b which may be arranged on a virtual plane surface vertical to a tool axis line; and being arranged at a position apart from the flat drag 44b on the peripheral edge of the front surface 42. A projecting part 48 i
