To solve the problems in the production of a Grignard reagent by using magnesium and an alkyl iodide compound having a proper boiling point.

The invention relates to a method for the production of a Grignard reagent by using tetrahydropyran as a reaction solvent and extraction solvent. A Grignard reagent can be produced easily from an alkyl iodide compound having a proper boiling point and magnesium by the invention and, accordingly, the cost of apparatus and equipment can be reduced and the reaction operation can be simplified by using the same reaction solvent and extraction solvent in the subsequent process. The invention further enables the reduction of the amount of the solvent by reusing the solvent and realizes the expansion, etc., of the application of high-polarity reaction raw materials.