Lactic acid removal device

A lactic acid removal device, comprising:

• a culture solution for cells or microorganisms;
• a vessel that contains the culture solution;
• and
• a lactic acid adsorbent disposed to be in contact with the culture solution, the lactic acid adsorbent being brought into contact with the culture solution and adsorbing lactic acid in the culture solution,
• the lactic acid adsorbent including at least one of (a) a layered double hydroxide that contains a plurality of metal hydroxide layers and also contains anions and water molecules held between the metal hydroxide layers, or (b) a layered double oxide that is an oxide of the layered double hydroxide,
• the metal hydroxide layers containing divalent metal ions M2+ and trivalent metal ions M3+,
• mole ratio (M2+/M3+) of the divalent metal ions M2+ to the trivalent metal ions M3+ in the layered double hydroxide being 1.9 to 3.3, and
• the mole ratio in the layered double oxide being 1.8 to 2.7.