Modified starches were used as additives to make tomato ketchup, and their effects on the rheological properties, serum separation and sensory characteristics of the tomato ketchup were examined. The magnitudes of the yield stress and the consistency index of the tomato ketchup with the additives, regarded as a Herschel-Bulkley fluid, were found to be in the order of ADA(acetylated distarch adipate)$gt;SA(starch acetate)$gt;HDP(hydroxypropyl distarch phosphate)$gt;RCS(raw corn starch)$gt;NS(no starch). The flow behavior indices of SA added ketchup and HDP added one were nearly constant regardless of the additive concentrations, whereas those of ADA and RCS increased with the additive concentration. In the serum separation test by centrifugation, the ADA added ketchup showed the highest stability against separation, being followed by SA$gt;HDP$gt;RCS$gt;NS. In the sensory evaluation, the magnitudes of the acceptance of the ketchup with the additives were as ADA(2%)$gt;SA(2%)$gt;RCS(2%)$gt;NS$gt;HDP(2%).