Process for producing nickel powder

A process for producing nickel powder, comprising a crystallization step including obtaining nickel crystal powder formed by a reductive reaction in a reaction solution in which at least a water-soluble nickel salt, a metal salt of a metal more noble than nickel, hydrazine (N2H4), an alkali hydroxide, an amine compound, a sulfide compound, and water are mixed,

• wherein:
• the amine compound is an autolysis inhibitor of the hydrazine,
• the amine compound contains two or more primary amino groups (—NH2) in the molecule, or contains one primary amino group (—NH2) and one or more secondary amino groups (—NH—) in the molecule,
• a ratio of a molar number of the amine compound with respect to a molar number of nickel in the reaction solution is in a range of from 0.01 mol % to 5 mol %,
• the sulfide compound is an autolysis inhibition adjuvant of the hydrazine,
• the sulfide compound contains one or more sulfide group (—S—) in the molecule, and
• a ratio of a molar number of the sulfide compound with respect to the molar number of the nickel in the reaction solution is in a range of from 0.01 mol % to 5 mol %.