To provide a novel diamine, and a polyimide precursor and a polyimide using it. A diamine represented by the formula (1): wherein each of X1 and X5 which are independent of each other, is a single bond or the like; each of X2 and X4 which are independent of each other, is —CH2— or the like; X3 is a C1-6 alkylene or the like; each of Y1 and Y2 which are independent of each other, is a single bond or the like; R is a C1-20 linear, branched or cyclic hydrocarbon group; and a is 0 or 1).