Method of inspecting a body having fine-gap grooves and method of repairing the body

A method of inspecting a molding die for producing a honeycomb structure body of a predetermined shape, the molding die having a plurality of through holes formed in parallel to each other, each through hole being comprised of a feed hole and a slit groove having a flow through passage smaller than a flow through passage of said feed hole, wherein a molding material is fed through the feed holes to extrude the molding material through the slit grooves during the production of the honeycomb structure body,

• the method comprising steps of:
• irradiating parallel light from a feed hole side of the molding die toward a slit groove side of each of the through holes so that the parallel light passes in parallel through all of the through holes;
• measuring, at the slit groove side of the molding die, an amount of the light passed through at least some of the through holes;
• detecting the presence of an abnormal part in at least one slit groove of the plurality of through holes irradiated based on a difference in the amount of light measured for the respective through holes.