Nobutora took an aggressive diplomatic policy; he welcomed the daughter of a court noble Kinyori SANJO as the wife of his heir Harunobu (Shingen), and promoted a marriage policy and made alliance with the Imagawa clan who had power over the neighboring district.
嫡男・晴信（信玄）に公家の三条公頼の娘を迎え、婚姻政策を展開して今川氏などの近隣勢力と同盟を結ぶなど、積極的な外交政策をとった。