The international tourism develops rapidly in recent years, but relatively few efforts have been paid on theoretical studies. This paper combines the microeconomics theory and social psychology to formulate the pleasure travel utility function and the decision model of tourists by considering the attributes of travel destinations, in-flight travel time, etc. The tourists are assumed to make their travel decisions by maximizing their utilities subject to income and time constraints. Nonlinear mathematical programming techniques are used to examine the optimization condition and to obtain the optimal solutions of decision variables--travel distance between origin and destination and travel expenditure. The results of elasticity analyses show that the increase in the tourist's income will expand the values of decision variables, but at a declining expansion rate. On the other hand, the raised daily expenditure will shrink the travel distance and travel expenditure at an increasing shrinkage rate. The effects of variations in saving amount are higher when tourist incomes are lower. Finally, the pleasure travel time will decrease when the daily consumption cost of travel destination is high.

國際觀光旅遊蓬勃發展的近年，相關性的理論研究仍少見。本研究結合個體經濟學與社會心理學的理論觀念，透過對觀光旅客的社經條件與旅遊偏好、觀光據點的旅遊特性、飛行時間等因素的考慮與其相互關係的探討，構建觀光旅客的旅遊效用函數與決策模式。模式假設觀光旅客在追求效用極大下，考慮所得及時間限制作旅遊決策，並以非線性數學規劃技巧檢視最適化條件，求解最適決策變數－旅行距離、旅遊支出。經由對最適決策變數分析與彈性分析結果顯示，所得增加將使旅行距離、旅遊支出增加，但其增加的變化將減緩，且在低所得時受儲蓄額變動的影響較大；而日常支出增加將使旅行距離、旅遊支出減少，但減少程度會隨之擴大。而觀光據點的每日消費水準較高時，會縮短觀光旅遊的時間。