Disclosed is a toner comprising at least a resin and a coloring agent, wherein the resin comprises toner particles in which a polyester resin unit is cross-linked by a diatomic cross-linking group expressed by a following general formula (1): —X1Y1X1— [wherein in the formula, X1 denotes a linking group; and Y1 denotes a radical polymer unit having a number average molecular weight Mn ranging from 5000 or more to 50000 or less, and a ratio Mw/Mn ranging from 1.0 or more to 1.2 or less, wherein Mw denotes a weight average molecular weight, and Mn denotes the number average molecular weight].