To reduce a time required for repairing a honeycomb core sandwich panel. A repair method according to the present invention is a repair method, in which a repair patch 20 is disposed on a repair target portion that exists on the side of a repair surface 1A of a honeycomb core sandwich panel 1, the honeycomb core sandwich panel 1 being formed by sandwiching a honeycomb structured core 10 with a plurality of cells between skins 11 and 12, the method including: a heating step of heating the repair patch 20; and a cooling step of cooling the honeycomb core sandwich panel 1 from the side of a second surface 1B opposing the repair surface 1A of the honeycomb core sandwich panel 1.