科技不斷的進步，智慧型手機與3G網路的普及造就了App的市場，本研究主要是探討以App為例功能投資與品質投資的成本效益模式。藉由分析投資於功能與品質所能產生的預期投資報酬，將投資功能與品質廣泛衡量，並且量化，分析投資於功能與品質所產生之效益關係，用模型提供企業管理者投資決策之助力。App被設計出來，所重視的即是本身的功能，若達到顧客的需求，顧客滿意度與忠誠度則會提升，進而購買意願增加並提升市場佔有率與顧客需求量，相對的企業可利用降低App之Bug率，達到減少顧客抱怨、造就好口碑。 本研究將降低Bug率與提升功能兩者相結合，所發展出的投資模式為架構，並探討兩者相結合之聯結模式，進而求出投資利潤，以助決策者在功能投資與品質投資之間該如何衡量，以達到公司目標方針。最後舉數值例子分析，用以獲得本研究之投資模式的最適解，並說明其模式在各數值例子下之結果與意義，可作為後續研究與實務應用之參考。 With the evolution of technologies, smart phone and 3G network were spread widely and created the market of App. This research is to discuss the cost/benefit model of function investment and quality investment in the case of App market. Through analysis the expected investment repay caused by investing in function and quality, we can quantity and measure the effect and benefit generated by the investment, then provide a mathematical model which can assist making investment decisions to entrepreneurs. App is designed to provide its own functions. If it reaches customers’ requirements, customer satisfaction and customer loyalty will rise, then boost the purchase intention, market share and customer demand; in addition, enterprises can achieve the objectives of decreasing customer complaint and making good word-of-mouth level by decreasing the bug rate. We develop an investing structure model in the research by combining the adjustment of bug rate and function, then find the investing revenue to help decision makers find an optimal balance between function investment and quality investment to achieve the objectives. Finally, we give examples to find an optimal solution in this investment model, and explain the output and meaning of the examples in each model.