Production method for thiocarbonyl compound

Provided is a method with which it is possible to produce a high-purity thiocarbonyl compound via an industrially practicable production method by removing a sulfurizing agent-derived byproduct via a simple post-reaction purification method. This production method for a thiocarbonyl compound (B) includes, in the following order: a step (1), in which a carbonyl compound (A), a diphosphetane-disulfide compound (C), and a solvent (X) are heated, yielding a mixture; and a step (2), in which the mixture is alkali-treated with an alkali aqueous solution having a concentration of at most 25 wt%.