In this paper, we propose a new near-field reader antenna for 900 MHz RFID. The proposed antenna consists the micro-strip antenna with the periodic structure. The overall dimension of the antenna is $313mm{ imes}152mm{ imes}14mm$. The antenna has the uniform E-field distribution in near field region and the heart-shaped radiation beam pattern (Peak gain=-2 dBi). The transmitted power range is from 17 dBm to 23 dBm. We focus on minimizing the detected error by suppressing the reflected power from the metal, which is attached to the surface by tag, and by reducing the transmitted power from tag.