The Karatsu Line (唐津線, Karatsu-sen) is a regional railway line in Saga Prefecture, Japan, owned and operated by Kyushu Railway Company (JR Kyushu).

The Karatsu Kogyo Railway opened a line from Myōken (妙見) (today Nishi-Karatsu to Yamamoto in 1898, on an alignment paralleling the west bank of the Matsuura River, and extended the line to Taku the following year.

In 1902, the company merged with the Kyushu Railway Co., which extended the line to Kubota in 1903.

[4] The Chikuhi Line from Higashi-Karatsu was extended to Yamamoto in 1929 on an alignment paralleling the east bank of the Matsuura River.

[5][6] In 1983, the Chikuhi line was rebuilt so it branched at Karatsu,[5] with the Karatsu - Nishi-Karatsu section being electrified at 1,500 V DC at the same time in conjunction with the electrification of the Chikuhi line, together with CTC signalling from Nishi-Karatsu to Kubota.