Abstract-This paper presents an investigation of prediction of cutting force and tool deflection in micro flat end milling. To predict cutting forces specific cutting force coefficients KT and KR were used. In fact, various cutting forces prediction models were proposed in past researches for conventional sized machining processes. However, micro end-milling processes were known as different phenomenon as respect to macro end-milling. Many past researches concerned complicated different models for micro end-milling from macro end-milling. However, cutting force models for both macro and micro end milling were fundamentally based on measured cutting forces for a series of experimental machining processes. Then, cutting force model proposed by Tlusty, which was developed for macro end-milling, was applied for micro flat end milling because this model is relatively simple. Finite element method was used to predict tool deflection based on predicted cutting forces. Predicted tool deflection amounts and actual machined profiles were compared each other in order to check out the differences between them.Index Terms-Cutting force, micro end-mill, finite element method, tool deflection.