The invention provides a process for production of mirtazapine as a convenient process for obtaining mirtazapine from a reaction mixture obtained by cyclization of 2-(4-methyl-2-phenylpiperazin-1-yl)pyridine-3-methanol with concentrated sulfuric acid, at high purity and in a form suitable for safe use as a drug.The production process for mirtazapine is characterized in that a reaction mixture obtained by cyclization of 2-(4-methyl-2-phenylpiperazin-1-yl)pyridine-3-methanol with concentrated sulfuric acid is diluted with water, the dilution is alkalinized in the presence of propanol, the mirtazapine is extracted with propanol and the mirtazapine is crystallized from the extract.