Production method of product and product

A production method for a product, comprising:

• culturing cells,
• wherein the production method for a product is perfusion culture in which a cell density at a time of production of the product is 80×106 cells/mL or more and 300×106 cells/mL or less, where a period of the perfusion culture is 13 days or more and 500 days or less,
• in a period of at least one day or more in the period of the perfusion culture, X [mol/L/day], which is an alkali addition rate per day, is controlled in a range of 0≤X<0.029, where a pH of an aqueous alkali solution to be added satisfies 7<pH<13,
• wherein in a case where a pH of a culture solution decreases in a case where the culturing is carried out without adding an alkali, a culture medium to which an alkali is added is supplied to control the pH of the culture solution, and
• wherein the method further comprising supplying a culture medium to which an alkali of 1.0×10−3 to 2.0 mol/L is added, in a case where a pH of a culture solution is less than 6.85.