A total of 2,260 specimens of Aristeus virilis were collected monthly at the Daishi fish market in I-lan from January to September 2010. Seasonal growth parameters, mortality, exploitation rate, and recruitment pattern of this species were estimated from the length-frequency data with ELEFAN. Parameters of the von Bertalanffy growth equation with seasonal fluctuations were estimated as follows: asymptotic length (L∞) = 7.25 cm (carapace length), growth coefficient (K) = 0.39 yr-1, amplitude of growth oscillation (C) = 0.8, winter point (WP) = 0.2, and L∞ = 5.04 cm, K = 0.44 yr-1, C = 0.8, WP = 0.2 for females and males, respectively. The total mortalities (Z) estimated by using the length-converted catch curve were 1.17 yr-1 and 1.23 yr-1 for females and males, respectively. The natural mortality (M) estimated from life history models was 0.42-0.65 yr-1. The fishing mortalities (F) were 0.52-0.75 yr-1 and 0.58-0.81 for females and males, respectively. The exploitation rates (E) for females and males were 0.44-0.67 and 0.47-0.66, respectively. The recruitment pattern suggested that recruitment occurs twice a year.