Running mostly on the flatlands, the Kusatsu Line between Mikumo Station and Kibugawa Station runs through mountains and narrow woods along the river, parallel to the Old Soma Highway (旧杣街道) (in fact, the entire line runs along the Soma Highway).
比較的平地を走るが、三雲～貴生川間では山と川の狭間の林を縫って旧杣街道と併走する（実際、全線が杣街道の道筋に沿って走っている）。