Valproic acid is widely used as an antiepileptic drug. However, valproic acid use during pregnancy increases the risk of neurodevelopmental disorders in the offspring. In this study, we examined the effects of valproic acid on retinal development in neonatal mice. Mice were subcutaneously injected with valproic acid or vehicle once a day from postnatal day (P) 0 to P7. The mice were sacrificed on P4, P8, P14, and P21. Until P8, the cell number in the ganglion cell layer and the thickness of retinal layer decreased in mice treated with valproic acid. On P8, the outer plexiform layer was evident in vehicle-treated mice but was not apparent in valproic acid-treated mice. The numbers of bipolar and horizontal cells in valproic acid-treated mice were significantly less than those in vehicle-treated mice. The appearance of immunoreactivity for synaptophysin (a presynaptic marker) in the outer and inner plexiform layers was delayed in valproic acid-treated mice. These results suggest that exposure to valproic acid during retinal development leads to the acceleration of developmental cell death and the delay in synaptogenesis in the retina. Therefore, when neurologists prescribe valproic acid for epileptic pregnant women, they should pay special attention to the increased risk of inducing visual dysfunction in their babies.