Abstract: A deck-slab waterproofing-membrane application brush for coating highway-bridge deck slabs with a waterproofing membrane, and a deck-slab waterproofing-membrane application apparatus for towing the brush to spread on waterproofing product are made available to enable the applying of deck-slab waterproofing membranes uniformly, safely, and efficiently to highway bridges. The deck-slab waterproofing-membrane application brush, for spreading on highway-bridge deck-slab waterproofing product, is characterized in that inside a furrow in a furrowed metal plate, numerous metallic bristles are aligned into rows in a packed, sheet-like form and fastened in a state in which the numerous metallic bristles are clamped.