To estimate the biological reference points, suitable for fisheries management of sandfish Arctoscopus japonicus in the East Sea of Korea, we simulated the yield-per-recruit (Y/R) from age 0 to 6 (0?2,555 days). The stimulation was based on two instantaneous natural mortality conditions: size-dependent (Mt, d-1) and constant (Mcons, d-1); Subsequently, the biological reference points of the two mortality conditions was compared. Mt decreased from 0.0075 d-1 to 0.0018 d-1 depending on growth, and Mcons remained constant at 0.0011 d-1 for all ages. Our Y/R model showed that the maximum yield of Mcons was 14 times higher than that of the Mt. The length at first capture to maximize the harvest at the F0.1 points of the two natural mortality conditions was Lc,t=10.2 cm (TL) and Lc,cons=17 cm (TL). We concluded that Mt was more suitable for estimating M than Mcons; this is because Lc,t showed minimal difference from the current fishing regulations (11 cm, TL), and Mt reflected more biological characteristics than Mcons. We suggest that 10.2 cm and 0.8 as the suitable length at first capture and corresponding age, respectively for efficient fisheries management of sandfish.