In this study, we quantitively examined whether the introduction of telework following the outbreak of COVID-19 reduced communication of gratitude within a Japanese company. Since the company introduced company-wide teleworking after the outbreak of COVID-19, we hypothesized that communication of gratitude decreased because of the difficulty in informal communication under teleworking. We analyzed behavioral data from an annual event held at the company, where employees send messages of gratitude freely to each other. First, results showed that the amount of the messages of gratitude per person in 2020 was smaller than that in 2019. Second, the messages was also found in the organizational newcomers who entered the company in 2020, compared with the newcomers in 2019. We discuss the implications of these findings for practice of company-wide teleworking under and after COVID-19.