A fuel rod and a fuel assembly for light water reactors, in which crack penetration to a fuel cladding tube or an end plug can be prevented, are provided. The fuel rod 10a includes: a cylindrical cladding tube 11 formed of a ceramic base material; a connection 21 formed of the same material as the cladding tube 11; and an end plug 12a having a concave portion 12f of a continuously curved surface shape adapted to house the connection 21. The end plug 12a is formed of the same material as the cladding tube 11. A slanted surface 11a formed at an end portion of the cladding tube 11, and a slanted surface 12d formed at an end portion of the end plug 12a are joined in contact with each other with a metallic joint material 20. The joint is supported by the connection 21.