To prevent the failures of synthesis owing to the shortage of a solvent or a reagent.

A reaction block 1 in which reactors 2 are arranged and a liquid supply part 3 for supplying reagents and a solvent stored in reagent containers 6, 7 and a solvent container 8 to the reactors 2 are provided, and the reaction is carried out in the reactors 2 while the reagents and the solvent are supplied from the containers 6, 7 and the container 8 to the reactors 2 according to a set synthetic protocol. The quantities of the reagents and the solvent stored in the containers 6, 7 and the container 8 are stored in a liquid quantity memory part 26, a liquid quantity detection part 27 compares the quantities of the reagents and the solvent to be supplied to the reactors 2 with the quantities of the reagents and the solvent stored in the memory part 26 to detect the shortage of the reagents and the solvent, and a liquid shortage dealing part 28 takes prescribed measures in case of the shortage of the reagents and the solvent.