This study was conducted to select candidates from plant resources for the purpose of improving or treating Alzheimer's disease, a type of dementia. One hundred and eighty-four plant extracts at a final concentration of $100{\mu}g/ml$ were screened to determine their capacity to inhibit acetylcholinesterase (AChE) by in vitro assay. From this AChE assay, seven plant extracts - including methanol ext. and water ext. of Phellaodendron amurense Rupr. (bark), methanol ext. of Nelumbo nucifera Gaertn (stamen/ovary), methanol ext. of Persicaria tinctoria H. GROSS (flower), methanol ext. of Coptis chinensis (rhizome), ethanol ext. of Cinnamomum cassia Blume(bark) and ethanol ext. of Carthamus tinctorius L. (fruit) - showed effective inhibition activity ranging from 18.7% to 63.1%. The selected extracts were testified their inhibition activities on AChE and BuChE (butyrylcholinesterase) at concentrations of 25, 50, 100, $200{\mu}g/ml$. In the AChE assay, five extracts including methanol ext. of Nelumbo nucifera Gaertn. (stamen/ovary), methanol ext. of Persicaria tinctoria H. GROSS (flower), methanol ext. of Coptis chinensis (rhizome), methanol ext. and water ext. of Phellaodendron amurense Rupr. (bark) showed inhibition activity of 15.0%~73.5%, 19.5%~63.5%, 81.6%~58.5%, 69.9%~80.5%, and 54.8%~78.3%, respectively, at concentrations of 25, 50, 100, $200{\mu}g/ml$. In the BuChE assay, the extracts of Nelumbo nucifera Gaertn. (stamen/ovary), Persicaria tinctoria H. GROSS (flower), and Coptis chinensis (rhizome) showed inhibitory capacities of 58.9~81.6%, 45.8%~72.4%, and 33.1%~55.4% at concentrations of 25, 50, 100, $200{\mu}g/ml$, respectively. In conclusion, it is suggested that Nelumbo nucifera Gaertn. (stamen/ovary), Persicaria tinctoria H. GROSS, Coptis chinensis (rhizome) and Phellaodendron amurense Rupr. (bark) could be selected as candidate materials for improving or treating Alzheimer's disease on the basis of further study.