The objective of this study is to show detailed analyzed results about the relations between upstream migration of sweetfish and water temperature at Nagara river, which were used in the study of Suzuki et al. (2014). Daily number of upstream migration data of sweetfish at Nagara river barrage, water temperature data at Ise-Oohashi bridge from water information system, and sea surface temperature (SST) at Ise Bay by Mie Prefecture Fisheries Research Institute were used. SST has good correlation with the total number 1% excess date. As SST becomes higher, the date becomes late. River water temperature has good correlation with the first group 5% excess date. As the river water temperature becomes higher, the date becomes early, which is the reverse tendency to SST. Water temperature difference (sea-river) has the good correlation with the first group 5% excess date. As the water temperature difference becomes higher, the upstream migration date becomes early. By these analyses, it is concluded that the first group 5% excess date is an effective index for the upstream migration start timing, and that water temperature difference (sea-river) is an effective water temperature index for the migration.