Provided are a method and an apparatus of supplying a resin material for a compression molding apparatus which is capable of evenly supplying a resin material to a cavity. An upper slit plate (31) including a resin maintaining tray (21) and a resin maintaining part (33) in a slit shape is overlapping with a lower slit plate (32) having an opening part (34) in a slit shape and a non-opening part (35), wherein the non-opening part (35) in the lower slit plate (32) is disposed to cover the resin maintaining part (33) in the upper slit plate (31). As such, granular resin is supplied to the resin maintaining part (33). The resin maintaining plate (21) is disposed on the cavity (121) in the compression molding apparatus, and, with respect to the cavity (121), the lower slit plate (32) is moved in a direction perpendicular to a longitudinal side of the resin maintaining part (33) in the slit shape. As the opening unit (34) in the lower slit plate (32) is moved with respect to the cavity (121), the granular resin in the resin maintaining part (33) is evenly supplied to the inside the cavity (121).