在營造廠的角度下，營建成本的組成可以分為三個部份：結構建材機電的直 接成本、配合建造過所衍生及管理專案所需的間接成本及專案利潤。 在營建成本估算中，直接成本是可以依照當下的市場現況價值、實際的施作 數量精準的估算出來。但間接成本因為是配合直接成本及管理需要下所衍生出來 的，因此在目前市場估算的方式大多是以一定的比例數乘以直接成本的總額，在 這樣的估算方式下因為不像直接成本有市場價格及施作數量做為基礎，因此在完 工結案時無法準確的了解間接成本結餘或超用的因素為何。 成本會計的主要功能是提供企業內部管理階層釐訂決策之資訊，其同時提供 對外報告編製時所需之成本資訊，就目前市場上的營建專案在成本會計分析上大 多採用分批成本會計或分步成本會計這樣的傳統成本制度，在傳統成本制度下看 營建成本只能看出單個專案的直接成本及間接成本分別的總額，針對其直接成本 對間接成本的發生是否有直接影響並無法得知。 本研究希望能透過作業基礎成本制（Activity-Based Costing）分析營建專案直 接成本與間接成本相互影響的因素為何？期望能達到下列目的： 1. 製作出專案作業成本庫 2. 找出專案成本控制的重點 3. 提供給專案決策者管理建議的方向;In construction, the project cost estimates are broken down into direct costs and indirect costs. Direct costs are directly attributable to construction activities, which consists of the costs of materials, labor, and equipment. They all directly involved efforts or expenses for undertaking site activities. On the other hand, indirect costs are not directly attributable to construction activities, but in various degrees are conditional to them. Indirect costs are typically allocated to a cost item on a certain basis, by means of a percentage of the direct cost item. In construction, all costs which are required for completion of the project, but are separated to the direct construction activities, such as overhead and a number of time related cost items. Due to the thin profit margins in construction industry, contractors are encountering a tremendous difficulty in estimating the precise range of indirect costs. This cost estimate endeavor controls the sustainability of a contracting business: over-estimate would limit the likelihood of winning a bid; under-estimate would forego the chance of making a profit. Therefore understanding the clear and complex linkage between a direct cost item and the related indirect cost is crucial in successful cost estimation. This research undertakes this problem by employing the well accepted principle of Activity-Based Costing (ABC). By in-depth analysis of four construction projects, the different aspects of linkage between direct cost and indirect cost are investigated. By using table comparison and incorporating site interviews, this research provides comprehensive recommendations concerning the estimate of indirect costs. This research also identifies a number of issues which are most relevant in mis-estimate of indirect costs in the past. It is concluded that ABC principle is very useful for the purpose of justifying indirect costs.
