A socket for an electrical part comprising: a socket body having a mount portion on which an electrical part having terminals is mounted; and a number of contact pins (15;35;16) to be contacted to or separated from the terminals of the electrical part wherein said contact pins (15;35;16) are arranged in shape of matrix having vertical and horizontal rows, the matrix arrangement having a rectangular outer edge portion and said socket body for an electrical part having a rectangular outer shape in a plan view in a usable state, respective side portions of the rectangular outer edge portion of the matrix arrangement and respective side portions of the rectangular outer shape of the socket body are substantially parallel to each other, and wherein each of said contact pin (15;35;16) is formed with an elastic piece (15a;35a;16a,16b) having, at a front end portion thereof, a contact portion (15d;35d;16e,16f) contacting to or separating from the terminal of the electrical part and said contact portions (15d;35d;16e,16f) of the elastic pieces (15a;35a;16a,16b) of the respective contact pins (15;35;16) have a displaced direction which has predetermined angles with respect to the arrangement direction of the vertical and horizontal rows of the contact pins (15;35;16) in the matrix arrangement thereof, characterized by a movable plate disposed to the socket body to be movable perpendicularly with respect to the mount portion in a usable state of the socket said movable plate being provided with a cam portion wherein said elastic piece (15a;35a;16a,16b) is formed at a front end portion thereof with a contact portion (15d;35d;16e,16f) which is displaced by pressing the elastic piece (15a;35a;16a,16b) by the cam portion f the movable plate when the movable plate is moved perpendicularly. a socket body having a mount portion on which an electrical part having terminals is mounted; and a number of contact pins (15;35;16) to be contacted to or separated from the terminals of the electrical part wherein said contact pins (15;35;16) are arranged in shape of matrix having vertical and horizontal rows, the matrix arrangement having a rectangular outer edge portion and said socket body for an electrical part having a rectangular outer shape in a plan view in a usable state, respective side portions of the rectangular outer edge portion of the matrix arrangement and respective side portions of the rectangular outer shape of the socket body are substantially parallel to each other, and wherein each of said contact pin (15;35;16) is formed with an elastic piece (15a;35a;16a,16b) having, at a front end portion thereof, a contact portion (15d;35d;16e,16f) contacting to or separating from the terminal of the electrical part and said contact portions (15d;35d;16e,16f) of the elastic pieces (15a;35a;16a,16b) of the respective contact pins (15;35;16) have a displaced direction which has predetermined angles with respect to the arrangement direction of the vertical and horizontal rows of the contact pins (15;35;16) in the matrix arrangement thereof, characterized by a movable plate disposed to the socket body to be movable perpendicularly with respect to the mount portion in a usable state of the socket said movable plate being provided with a cam portion wherein said elastic piece (15a;35a;16a,16b) is formed at a front end portion thereof with a contact portion (15d;35d;16e,16f) which is displaced by pressing the elastic piece (15a;35a;16a,16b) by the cam portion f the movable plate when the movable plate is moved perpendicularly.