Abstract: A hot blast-furnace lining relining apparatus has a holding member that is to be horizontally inserted through an opening near the top of a blast furnace, a collapsible arm member held by the holding member, and a nozzle attached to the tip of the arm member for gunning monolithic materials onto such part of the furnace as requires repair. With the furnace load lowered below the point to be repaired, the arm member is inserted into the furnace, and then expanded. The gunning nozzle, which is directed to the damaged part of the furnace wall and rotated about the furnace axis, sprays monolithic materials onto the furnace linings to carry out the repair. On completion of the repair, the arm member is folded and taken out of the furnace.