This mixed methods study investigates Korean elementary school students’ foreign language learning demotivation and their teachers’ perception of student demotivation. A questionnaire was conducted for 6,301 elementary school students from Grades 3 to 6 to examine their motivational changes. This revealed a decrease in all motivational constructs – instrumental, intrinsic, integrative, parental/academic extrinsic motivations – as the students advanced throughout the school grades. The findings were further analyzed by using interviews and open-ended questionnaires with 17 English teachers. They attributed the students’ demotivation to three elements: 1) the negative impact of the English teacher such as incongruence with students’ needs, teachers’ impatience, and disinterest in teaching and in their students; 2) excessive social expectation of English proficiency; and 3) the widening English proficiency gap among the students.