PROBLEM TO BE SOLVED: To provide a subject authentication system in window transaction of a financial institution for eliminating individualistic determination of subject authentication by a window employee, and performing the subject authentication independently from a count system of the financial institution, and a transaction system thereof.SOLUTION: A subject authentication system in window transaction between a financial institution and a client is configured so that a subject authentication engine 3 which can transmit information to both of a client terminal 1 operated by a client, and a window terminal 2 operated by a financial institution, is installed independently from a count system 4 of the financial institution, and subject confirmation in window transaction is performed by checking and determining engagement of an authentication item 18 which is registered in the subject authentication engine 3 as authentication means 11 in advance by selection of the client, and the authentication item 18 subm
