Lead wire for narrow space insertion

To provide a lead wire for narrow space insertion that is easily inserted into an elongated small-diameter pipe or small-diameter tube such as an ultrasonic probe or an electrode catheter. The above-described problem is solved by a lead wire for narrow space insertion including a copper alloy wire having a conductor diameter within a range of 0.015 to 0.18 mm, and an insulating layer provided to an outer periphery of the copper alloy wire. A friction coefficient of an outermost surface layer of the insulating layer is within a range of 0.05 to 0.3, a tensile strength of the lead wire is withina range of 700 to 1,500 MPa, and a conductivity of the copper alloy wire is within a range of 60 to 90% IACS. [课题]提供容易插入至超声波探针、电极导管那样的细长的细径管道、细径导管内的窄空间插入用铅丝。[解决方案]通过一种窄空间插入用铅丝解决上述课题，该铅丝具有：导体直径为0.015～0.18mm的范围内的铜合金线；和，设置于该铜合金线的外周的绝缘层，前述绝缘层的最表面层的摩擦系数为0.05～0.3的范围内，前述铅丝的拉伸强度为700～1500MPa的范围内，前述铜合金线的电导率为60～90％IACS的范围内。