The 25μm pixel Imaging Plate (IP) is expected to apply to high-resolution transmission electron microscopy (HRTEM) because of its higher spatial resolution than the 50μm pixel IP. It seems that the 25μm pixel IP, which has wide dynamic range and good linearity, is effective for HRTEM with low exposure to reduce electron radiation damage. In order to apply the IP to the HRTEM appropriately, it is necessary to understand the detective efficiency of the IP. In this paper, signal to noise (S/N) ratio and detective quantum efficiency (DQE) of the 25μm pixel IP at accelerating voltages of 100, 200 and 1250kV are presented and a suitable amount of electron exposure for HRTEM is discussed.DQE is expressed as the comparative noise level (σi2/σo2) measured by the ratio of the mean-square fluctuation of incident electrons (σi2) to that of output signal (σo2). In this experiment, the distribution of the incident electrons was assumed to be Poisson statistics.