This study was conducted to investigate morphological characteristics and effects of temperature on the development of Piezodorus hybneri on soybean. The unibanded stink bug, Piezodorus hybneri, is a serious insect pest in soybean fields giving damage to seeds in pod and leaves of soybean lowering both quality and yield. Eggs were spherical and laid in two raws on the leaves and pods of soybean plants. Body lengths of females and males were 9.8 mm and 8.7 mm, respectively. Egg hatch rates were better in higher temperature within the range of examined temperatures, which ranged in $81.2{sim}93.2%$. The development periods of eggs at the temperatures of 20, 25, 30 and $35^{circ}C$ were 10.7, 5.0, 4.0, and 3.0 days, respectively. Mean developmental periods of 1st, 2nd, 3rd, 4th and 5th nymphs at $25^{circ}C$ were 3.2, 3.4, 3.4, 3.3 and 5.9 days, respectively. Development threshold and effective accumulative temperature were $13.3^{circ}C$ and 65.5 DD (day degree) for egg stage, $9.9^{circ}C$ and 322.8 DD for nymph stage, $10.7^{circ}C$ and 386.4 DD from egg to adult, respectively. Oviposition began from 10 days after emergence at $25^{circ}C$, and the longevity of female and male were 52.5 and 38.2 days, respectively. Total number of eggs and egg masses laid by a female at $25^{circ}C$ were 496 and 21.3, respectively, The longevity of adult female was shortened with increasing temperature, whereas the total numbers of eggs laid by a female were decreased.