Bioconcentration Factor (BCF) is known as important criteria for ecotoxicology on hazardous chemicals. But there is no standard method for determining BCF and reported BCFs were slightly different in accordance with authors. This study was performed with aims to determine BCFs on BPMC and Carbaryl. Carassius auratus(goldfish) be chosen as test organism and test period were 3-day, 5-day and 10-day. Extract solvents were n-hexane and acetonitrile. GC-ECD was used to detecting carbamates. The obtained results were as follows: 1. It was possible to determine short term BCF$_s$ of Carbaryl or BPMC through relatively simple procedure. 2. BCF$_3$ of Carbaryl in concentration of 1, 2, 5, 10 ppm were 0.34 $pm$ 0.06, 0.18 $pm$ 0.02, 0.10 $pm$ 0.01, 0.06 $pm$ 0.01 respectively. BCF$_5$ of Carbaryl were 0.34 $pm$ 0.05, 0.18 $pm$ 0.02, 0.13 $pm$ 0.01 and 0.07 $pm$ 0.01, BCF$_{10}3$ of Carbaryl were 0.45 $pm$ 0.05, 0.27 $pm$ 0.02, 0.16 $pm$ 0.02 and 0.09 $pm$ 0.01. BCF$_3$ of BPMC in concentration of 1, 2, 5 ppm were 4.66 $pm$ 0.17, 2.64 $pm$ 0.49, 1.88 $pm$ 0.24 respectively. BCF$_5$ of BPMC were 4.09 $pm$ 0.50, 2.42 $pm$ 0.37 and 1.83 $pm$ 0.15. 3. BCF$_s$ of BPMC were decreased as increasing concentration. However, BPMC concentration in fish were increased in contrast to BCF. But more concentrated BPMC was found in fish 3-day test than found concentration in fish 5-day test. 4. Same trend appeared in Carbaryl. BCF$_s$ of Carbaryl were decreased as increasing concentration and prolonging test period. But found Carbaryl concentration in fish were increased. 5. BCF$_s$ of BPMC were higher than that of Carbaryl by 10 times, in spite of the physicochemical properties of the two carbamates were similar to each other. Further study is recommended to find out the reason of the difference.