A total number of eighty gallic acid producing strains were isolated from forest soil or plant samples. Among these strains, thirteen isolates were selected for gallic acid production and these isolates were Aspergillus niger 1, A. niger 2, A. niger 3, Penicillium canescens (3), P. frequentans (2), P. spinulosum (2), P. purpurogenum (2), and P. zacinthae. By using eight of these strains and reference strain of A. niger NRRL 321, the production of gallic acid from oak tree (Quercus infectoria) gall nuts or sumac (Rhus coriaria) leaves were investigated. Maximum gallic acid yields from gall nuts were obtained for A. niger 3 (91.3%) and P. spinulosum (93.2%). In the case of sumac leaves, the reference strain A. niger NRRL 321 (46.1%) and P. zacinthae (48.2%) gave the highest gallic acid yields. To date, this study is the first report on production of gallic acid by these newly isolated Penicillium strains. Particularly, A. niger 3, P. spinulosum, P. purpurogenum and P. canescens may be used not only for gallic acid but also tannase production from tannin rich plant materials such as gall nuts. Their high yields and short incubation periods are also remarkable.