Some important observations have shown that the strong correlation between emerging flux and eruptions of quiescent filaments (Feynman & Martin, 1995; Wang & Sheeley, 1999). Chen & Shibata (2000) performed two-dimensional simulations including a flux rope in the corona, and their results suggest that the eruption process is triggered by the emerging flux through the reconnection. Our purpose in this paper is to investigate that '' how a filament is produced and how an eruption process can be initiated by the emerging flux and what effects of three-dimensionality appear in the process of eruption ''. For that purpose, we performed three-dimensional numerical simulations of the emerging flux model. nom our results, a filamentary structure is produced from the coronal arcade field by the reconnection process, and when the reconnection process proceeds effectively, the produced structure is ejected by the magnetic force. These processes can thought to be a new mechanism of the eruption which is different from, for example, the one in Fan & Gibson (2004).