Base on the survey and financial statement on fish-paste processing company, this study aimed to estimate management efficiencies of fish-paste processing management using a data envelopment-analysis (DEA), In-depth interview and to find out their determinants. Model results show that the estimated mean management efficiencies obtained for the VRS and CRS DEA are 83.7% and 89.1%. In-depth interview results also show that efficiencies caused by scale of technical matter was greater than efficiencies caused by the scale of the company. Thus it implies that technical development is essential for achieving high-efficiency of fish-paste processing company more than expanding the size of company.