NEW MATERIAL:A hitachimycin derivative shown by formula I (R1 and R2 are H or 2W6C alkanoyl with the proviso that R1 and R2 are neither H nor acetyl at the same time).

EXAMPLE: 11,15-Di-O-propionylhitachimycin.

USE: An antibiotic having excellent antitumor activity.

PREPARATION: Hitachimycin is reacted with an acyl halide of a carboxylic acid shown by the formula CnH2n+1CO2H (n is 1W5 integer) or an acid anhydride in the organic solvent containing no active hydrogen atom in the presence of a base at 10W90°C for 6W48 hours to give a compound shown by formula II (R1=R2=2W6C alkanoyl), which is reacted in an organic solvent in the presence of an acid or a base at 0W60°C for 1W30min to give a compound shown by formula III. Further this compound is acylated by the use of an acylating agent different from the above-mentioned acylating agent in the same way as above-mentioned to give a compound shown by formula IV (R1 and R2 are 2W6C alkanoyl and R1≠R2).