A process for production of mycophenolic acid is provided to increase production yield of mycophenolic acid by inhibiting wall growth and promoting MPA biosynthesis without overflow and contamination by using vegetable oil and unsaturated fatty acid instead of non-ionic surfactant. A mycophenolic acid represented by the formula(3) and its derivatives in which R1 is methyl or hydroxy methyl and R2 is hydroxy group or amino group are produced by culturing Penicillium brevi-compactum in a medium containing 1.0g/L or less, preferably 0.4-0.6g/L of vegetable oil selected from canola oil, corn oil and bean oil, or 20 g/L of 20g/L of oleic acid, and further containing assimilatable carbon source, nitrogen source and trace amounts of elements.
