Nagasaki 4th District (長崎県第4区, Nagasaki-ken dai-yon-ku) was a single-member electoral district for the House of Representatives, the lower house of the National Diet of Japan.
It was located in western Nagasaki and consisted of the cities of Sasebo, Hirado, Matsuura and Saikai, as well as Kitamatsuura District.
As of 2021, 250,004 eligible voters were registered in the district.
The district was redrawn twice between its creation in 1994 and its abolition, once in 2013 and once again in 2017.
The district was abolished during redistricting in 2022, and the areas it covered as of 2022 were transferred to the 3rd district.