A high-nervonic acid (cis-15-tetracosenoic acid, C24:1, n-9)-producing filamentous fungus of the Mortierella species was discovered among soil filamentous fungi. The filamentous fungal strain -RD000969- was isolated from soil collected in Kanagawa Prefecture (Japan) and was found to accumulate nervonic acid at a rate of 6.94% of the total cellular fatty acids. The base sequences of 28S rDNA D1/D2 and ITS 5.8S rDNA showed 100% homology with Mortierella capitata CBS 293.96. In addition to nervonic acid, strain RD000969 produced a large amount of long-chain monounsaturated fatty acids (C20:1, 12.22%; C22:1, 4.07%; C26:1, 5.91%) and a small amount of ultra-long-chain fatty acids (C28:1, 0.44%; C30:1, 0.06%; C32:1, trace). In the fungal cells, 98.87% of nervonic acid was localized at the sn-1,3 position of triacylglycerol. Nervonic acid production was maximum (186.3 mg·L(-1)) when the fungus was cultured in potato dextrose (PD) medium containing yeast extract, CaCl2, and MgSO4·7H2O.