Balanophora subcupularis Tam is newly discovered in the montane forest from Phu Hin Rong Kla National Park, Phitsanulok and Nam Nao National Park, Phetchabun. It is characterised by the reddish inflorescences, monoecious plant, 2–3 rows of tiny male florets occurring at the base of inflorescence, actinomorphic floret with (3–)4 perianth lobes and synandria with (3–)4 anthers. A taxonomic description, illustration, photographs and distribution are provided.