The purpose of this study is to find a way to improve students' performance to solve physics problems by inducing changes in emotion via immediate feedback. To this end, in 2016, we conducted an experiment, doing an interview and survey consecutively. The participants were five second-year male students attending a private high school in Seoul, Korea. The students solved three problems from a lesson on 'Force and Motion.' They were asked to express their emotions, both in words and using emoji stickers on their response sheets, so that we could investigate their emotions while they were solving physics problems. Almost all students were sensitive to emotions when attempting to solve difficult problems. To investigate the relationship between feedback, emotion, and confidence, immediate feedback was given after the students solved a problem. We found that the students' emotions were influenced by immediate feedback after solving physics problems. When given immediate feedback suggesting the correct answers, their negative emotions disappeared, and their confidence in their performance to solve problems increased. In this experiment, the students' emotions were controlled by immediate feedback. Therefore, this work suggests that students' performance can be improved by instilling confidence via emotional support.