In the present study, two investigations were conducted at a communication center, to examine white-collar workers' hemodynamic responses during working hours. In investigation I, hemodynamic responses were measured on a working day; and in investigation II, cardiovascular responses were verified on both working and non-working days. In investigation I, blood pressure, cardiac output, heart rate, stroke volume, and total peripheral resistance were measured in 15 workers during working hours (from 9:00 am to 18:00 pm) on one working day. Another 40 workers from the same workplace participated in investigation II, in which blood pressure and heart rate were measured between the time workers arose in the morning until they went to bed on 5 working days and 2 non-working days. The results showed that blood pressure increased and remained at the same level during working hours. The underlying hemodynamics of maintaining blood pressure, however, changed between the morning and the afternoon on working days. Cardiac responses increased in the afternoon, suggesting that cardiac burdens increase in the afternoon on working days. The present study suggested that taking underlying hemodynamic response into consideration is important for managing the work-related cardiovascular burden of white-collar workers.