Manufacturing method for plug for hole created in plate and plug for hole created in plate

A plug for a hole created in a plate, comprising a plugging member and a support plate, wherein

• the plugging member is formed of a size which is sufficiently large enough to cover the hole created in the plate,
• a protruding portion in bridge form is located on a rear surface of the plugging member in approximately a center portion by making a part of a member protrude from the rear surface of the plugging member,
• the protruding portion in bridge form protrudes in such a state that a gap is created between a bottom surface of the protruding portion in bridge form and the rear surface of the plugging member,
• the support plate is located through the gap in a direction from left to right in such a state that the support plate lies along the rear surface of the plugging member, and
• the support plate that lies inside said protruding portion in bridge form is formed of an elastic material in a band flat plate form from end to end as viewed from both the top and bottom surfaces of the support plate and wherein two ends of the support plate individually protrude equally right and left in a straight manner from the outer periphery of the plugging member, is positioned in such a state that a portion that is approximately at a center of the support plate is supported inside the protruding portion, and extends in the direction from left to right so that the two ends protrude to outside from an outer periphery of the plugging member, to form flat-plate shaped extension parts, so as to be able to be bent between fingers.