誠まことにありがとうございます

expression

thank you very much; we sincerely thank you

A polite, formal expression of gratitude. 誠に adds a sincere or official tone, so it is common in business, announcements, speeches, and service settings rather than casual thanks among close friends.

• 本ほん日じつはお越こしいただき、誠まことにありがとうございます。

  Thank you very much for coming today.

• ご協きょう力りょくいただき、誠まことにありがとうございます。

  Thank you very much for your cooperation.