A water-in-oil (W/O) emulsion ink which is suitable for use in inkjet printing and is low in viscosity and superior in storage stability is provided. The ink comprises an oil phase and a water phase emulsified in the oil phase using a nonionic surfactant, in which the water phase contains a salt of at least one metal selected from potassium or calcium. The metal salt is preferably a calcium salt, and particular preferably calcium chloride. The nonionic surfactant is preferably a polyglycerin fatty acid ester, and particularly preferably an esterification product of a polyglycerin and a hydroxy fatty acid. Preferably, the ink comprises 40-99 mass % of the oil phase and 60-1 mass % of the water phase, and contains a polyglycerin fatty acid ester in an amount of 0.5-40 mass % based on the total of the ink.