The effects of elevated CO₂ concentration on spiders were studied using third-instar spiderlings of the wolf spider Pardosa astrigera L. Koch 1878 in CO₂ climate chambers with two different concentrations of CO₂ (low, 370 ppm and high, 750 ppm). The food intake and total developmental period of spiderlings reared at high CO₂ concentration increased significantly, and the body length and weight of adult spiders decreased compared to those in the low-CO₂ group. The oviposition rate of female P. astrigera and the hatching rate of eggs did not differ between the high- and low-CO₂ groups, but the number of egg sacs and the total number of eggs produced by females from the high-CO₂ group decreased. These results suggest that elevated CO₂ concentrations are harmful to the growth, development, and reproduction of P. astrigera.