A copper alloy for terminals of the Cu—Ni—Sn—P system or Cu—Ni—Sn—P—Zn system and that has a tensile strength of at least 500 N/mm2, a spring limit of at least 400 N/mm2, a stress relaxation of no more than 10%, a conductivity of at least 30% IACS and a bending workability in terms of a R/t ratio of no more than 2. The spring portion or the entire part of such terminals are produced from the copper alloy, and have an initial insertion/extraction force of 1.5 N to 30 N and a resistance of no more than 3 m&OHgr; at low voltage and low current as initial performance. The terminals experience not more than 20% stress relaxation. The alloy is superior to the conventional bronze, phosphor bronze and Cu—Sn—Fe—P alloys for terminals in terms of tensile strength, spring limit, stress relaxation characteristics and conductivity and, hence, the terminals manufactured from such alloys have higher performance and reliability than terminals made of the conventional copper alloys for terminals.