The pinewood nematode, Bursaphelenchus xylophilus is a serious forest pathogen in many countries including Japan, China and Korea. To minimize the environmental problems caused by synthetic chemicals broadly utilized in the control of B. xylophilus, we estimated the nematicidal potency of 97 phytochemicals (49 monoterpenes, 17 phenylpropenes, 16 sesquterpenes and 15 sulfides) against B. xylophilus by measuring their inhibition activity against acetylcholinesterases (ACE, EC 3.1.1.7) of B. xylophilus (BxACEs). In the primary inhibition assay using B. xylophilus crude protein, (+)-α-pinene, (-)-α-pinene and 3-carene in the monoterpenes, ο-anisaldehyde and coniferyl alcohol in the phenylpropenes and cis-nerolidol in the sesquterpenes were observed the > 50% BxACE inhibition rate and they were subsequently estimated the inhibition rate against three recombinant BxACEs. The (+)-α-pinene and coniferyl alcohol showed the high inhibition rate against BxACE-1 and BxACE-2. Interestingly, coniferyl alcohol also exhibited the high inhibition rate against BxACE-3 which would be insensitive to ACE inhibitors.