Provided is a water based ink having a metallic lustrous color using an aluminum powder for a ballpoint pen which does not allow a discharging amount to reduce and splitting to occur. This water based ink contains an aluminum paste prepared by wetting aluminum powder in advance with at least one solvent selected from glycol ethers and glycols, a thickener, a water-soluble organic solvent and water. Further, provided is a water based pigment ink having a metallic lustrous color for a ballpoint pen in which an aluminum powder and a pigment are used and which allows the colorant to provide a well developed metallic lustrous color and can be used to draw beautiful lines. This water based pigment ink contains an aluminum powder, a water-soluble organic solvent, a pigment, a thickener and a resin emulsion.