Abstract: A retention device used in a circuit card of a computer is composed of a fixing board, an upper board surface of which is provided with a positioning hole having two ear parts at two sides; a positioning member, two sides of which are provided with shaft members which can be transfixed into shaft holes of the ear parts, and pressing surfaces at a lower part of which are pressed and in touch with a horizontal board surface of the fixing board. A projection piece which is extended from a metallic piece connected at a side of a circuit card is pressed by the positioning member which is rotated in the shaft holes with the shaft parts, to release the circuit card from being positioned and pressed, such that the circuit card can be easily taken out of the fixing board, thereby achieving a robustness in positioning the circuit card, along with a quick and convenient dismantling and assembling.