Abstract: The present invention provides a method of repairing a plaster ceiling. The plaster ceiling to be repaired by the above described method includes: plates bridged across joists and spaced apart from each other; a ceiling base material finished with a masonry trowel over the lower surfaces of the plates; and a ceiling finishing material formed over the lower surface of the ceiling base material. The above described method includes the steps of: drilling an injection hole extending from the upper surface of the plate to the interface between the plate and the ceiling base material; injecting an acrylic resin composition containing: at least one monomer selected from an acrylic monomer or an methacrylic monomer; a thermosetting resin; and a curing agent; through the injection hole into the interface between the plate and the ceiling base material; and curing the acrylic resin composition so that the plate and the ceiling base material are adhered to each other.