He also became a paragon of the Ii clan, which supported Edo bakufu (Japanese feudal government headed by a shogun) as a head fudai daimyo (a daimyo in hereditary vassal to the Tokugawa family) in the Edo period, and founded the base of modern day Takasaki City, Gunma Prefecture and Hikone City, Shiga Prefecture.
また、江戸時代に譜代大名の筆頭として、江戸幕府を支えた井伊氏の手本となった人物であり、現在の群馬県高崎市と滋賀県彦根市の発展の基礎を築いた人物でもある。