There is not much research on emotions of mathematics teachers other than the wide research on mathematics anxiety of mathematics teachers and pre-service teachers in elementary school. With the goal of beginning to fill this gap, this research pursues the aim of identifying the daily emotions in a classroom of a high school mathematics teacher. Data was gathered through audiotaped self-reports where the participant reported his emotional experiences during 13 mathematics classes. The data analysis show that the participant experienced diverse emotions such as satisfaction, disappointment, appreciation, happy-for, sorry-for, reproach and anger. The triggering situations for the cognitive appraisals are about the achievement of the planned activities for the lessons. The belief of the participant on the "good attitude" of students-perceived as students' "collaboration", "independence" and "participation"-supports the appraisals.