PURPOSE: To provide a stock control device capable of maintaining the stock of products securely, and easily within a proper stock range even in lot type production devices.

CONSTITUTION: The number of unfinished lots is calculated in Step S14 from a deviation number calculated in Step S12, and the number of expected stock at the completion of production is calculated in Step S16 from the number of the unfinished lot. It is judged in Step S18 whether the expected number of stock exceeds a reference stock upper limit. If the limit is not exceeded, the products of the unfinished lot number will be produced in Step S28. If it is exceeded, the number of unfinished lots will be reduced by one lot in Step S20, the number of expected stock will be also reduced by unit lot number in Step S22, and it is judged in Step S24 whether the expected stock number lowers the reference stock lower limit. If it is not lowered, the products of the unfinished lot number will be produced in Step S28 and, if it is lowered, the number of unfinished lots will be increased by one lot in Step S26 and the products of unfinished lot number will be produced in Step S28.