贾伊纳加尔（Jainagar），是印度比哈尔邦Madhubani县的一个城镇。总人口19493（2001年）。

该地2001年总人口19493人，其中男性10343人，女性9150人；0—6岁人口3161人，其中男1671人，女1490人；识字率58.26%，其中男性为67.33%，女性为48.01%。

Jainagar (Hindi: जयनगर also transliterated Jaynagar or Jayanagar) is a city and notified area in Madhubani district, Bihar State, India. It is situated on the holy Kamala River and has road and rail connections to India's main cities and to Nepal. The local language is Maithili. There are many temples in Jaynagar; the most notable are Durga Mandir (108 ft high and situated 2 km from the railway station), and Shilanath (famous for Lord Shiva) 4 km from the railway station near DB College.