NOVELTY - Secondary battery comprises a cathode (21), an anode (22), and an electrolytic solution. The cathode includes a cathode active material, where: the cathode active material includes a lithium phosphate compound (I); fine pore distribution of the cathode measured by a mercury intrusion method indicates a peak P1 in a range where a pore diameter is greater than or equal to 0.01 mu m and less than 0.15 mu m, and indicates a peak P2 in a range where the pore diameter is 0.15-0.9 mu m both inclusive; and a ratio I2/I1 between intensity I1 of the peak P1 and intensity I2 of the peak P2 is 0.5-20 both inclusive.    USE - The secondary battery is useful: as a lithium secondary battery; and in a battery pack, an electric vehicle, an electric power storage system, an electric power tool, and in an electronic apparatus as an electric power supply source (all claimed).    ADVANTAGE - The secondary battery exhibits superior battery capacity, high energy density, superior cycle characteristics, superior conservation characteristics, superior safety at the time of high-rate charge and discharge.    DETAILED DESCRIPTION - Secondary battery comprises a cathode, an anode, and an electrolytic solution. The cathode includes a cathode active material, where: the cathode active material includes a lithium phosphate compound of formula (LiaM1bPO4) (I); fine pore distribution of the cathode measured by a mercury intrusion method indicates a peak P1 in a range where a pore diameter is greater than or equal to 0.01 mu m and less than 0.15 mu m, and indicates a peak P2 in a range where the pore diameter is 0.15-0.9 mu m both inclusive; a ratio I2/I1 between intensity I1 of the peak P1 and intensity I2 of the peak P2 is 0.5-20 both inclusive; and porosity of the cathode is 30-50% both inclusive.    M1 = Fe, Mn, Mg, Ni, Co, Al, W, Nb, Ti, Si, Cr, Cu or Zn; and    a = 0-2; and    b = less than 1    INDEPENDENT CLAIMS are also included for:    (1) an electrode comprising the active material, where the active material includes (I);    (2) a battery pack comprising: the secondary battery; a control section controlling a used state of the secondary battery; and a switch section switching the used state of the secondary battery according to an instruction of the control section;    (3) an electric vehicle comprising: the secondary battery; a conversion section converting electric power supplied from the secondary battery into drive power; a drive section operating according to the drive power; and a control section controlling a used state of the secondary battery;    (4) an electric power storage system comprising: the secondary battery; at least one electric device supplied with electric power from the secondary battery; and a control section controlling the supplying of the electric power from the secondary battery to the electric devices; and    (5) an electric power tool comprising: the secondary battery; and a movable section which is supplied with electric power from the secondary battery.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view illustrating a configuration of a secondary battery (cylindrical type) including an electrode.    Electrode body (20)    Cathode (21)    Anode (22)    Separator (23)    Cathode lead (25)