Corrosion inhibitor and covered electrical cable with terminal

[Problem] To provide: a corrosion inhibitor that consistently protects a metal surface even if exposed to high temperatures, thereby maintaining anticorrosive performance, and that remains adhered to the metal surface even in hot and cold environments, thereby maintaining anticorrosive performance; and a covered electrical cable with a terminal, the anticorrosiveness of said covered electrical cable having been improved using said corrosion inhibitor. [Solution] This corrosion inhibitor includes: a viscous substance (A) that is made from a lubricant base oil and an amide compound; a composition (B) of a metal and a phosphorus compound, said phosphorus compound comprising one or more of the compounds expressed in general formulas (1) and (2); and a tackifier (C), wherein the mass ratio of (A) to (B) is within the range of (A):(B) = 50:50 to 98:2, and the included amount of (C) is 2 to 20 parts by mass per 100 total parts by mass of (A) and (B) together.