Disclosed is a proliferation-enhancing agent and/or a survivability-improving agent for a lactic acid bacterium belonging to the genus Lactobacillus, which comprises ?-caseinoglycopeptide as an active ingredient. Conventional survivability-improving agents such as antioxidative agents have undesirable influence on the flavors or physical properties of food compositions and exhibit the effects thereof through self-oxidation, and therefore cannot exhibit the effects thereof for a long period. The agent is expected to exhibit an excellent effect of enhancing the proliferation of a lactic acid bacterium or the like and/or improving the survivability of the lactic acid bacterium or the like for a prolonged period without affecting the flavors or physical properties of food compositions.
