电阻率（英语：Resistivity），又称电阻系数、导电率（非电导率），是描述材料导电性能的物理量。

电阻率在数值上等于单位长度、单位截面的某种物质的电阻，数值上等于长度为一米，横截面为一平方米的该种物质的电阻大小。

电阻率的倒数为电导率。电阻率与导体的长度、横截面积等因素无关，是导体材料本身的电学性质，由导体的材料决定，且与温度有关。

电阻率在国际单位制的单位是Ω·m，读作欧姆米，简称欧米。常用单位为“欧姆·厘米”。

电阻率较低的物质称为导体，常见导体主要为金属，而自然界中导电性最佳的是银。其他不易导电的物质如玻璃、橡胶等，电阻率较高，一般称为绝缘体。介于导体和绝缘体之间的物质（如硅）则称半导体。

Electrical resistivity (also known as resistivity, specific electrical resistance, or volume resistivity) is an intrinsic property that quantifies how strongly a given material opposes the flow of electric current. A low resistivity indicates a material that readily allows the flow of electric current. Resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm⋅metre (Ω⋅m) although other units like ohm⋅centimetre (Ω⋅cm) are also in use. As an example, if a 1 m × 1 m × 1 m solid cube of material has sheet contacts on two opposite faces, and the resistance between these contacts is 1 Ω, then the resistivity of the material is 1 Ω⋅m.