Yokoseura (横瀬浦) is a port located at the northern tip of the Nishisonogi Peninsula on the Japanese island of Kyushu, administratively under Saikai city, Nagasaki Prefecture. It was developed as an entrepot by the Portuguese in 1562 with the permission of the local lord Ōmura Sumitada, but was burned down a year later during a rebellion against Sumitada.