NOVELTY - Manufacture of phosphoric acid compound involves preparing raw material containing lithium superoxide, phosphorus pentoxide, manganese dioxide, iron(III) oxide, cobalt(II, III) oxide, nickel oxide, and zinc oxide, calcium oxide, magnesium oxide, zirconium dioxide and/or titanium dioxide, heating the prepared raw material, obtaining molten material by melting, obtaining solidified material by cooling molten material, pulverizing solidified material and obtaining ground material, and obtaining particles containing crystals with olivine structure by heating the ground material.    USE - Manufacture of phosphoric acid compound used for positive electrode active material for secondary battery (all claimed) e.g. lithium ion secondary battery, metallic lithium, secondary battery and lithium polymer secondary battery. Uses include but are not limited to electric vehicle, hybrid vehicle, plug-in hybrid motor vehicle and storage battery for electric power storage.    ADVANTAGE - The method enables efficient manufacture of phosphoric acid compound having excellent electroconductivity and ionic conductivity, and suppresses the structural change during charging/discharging. The secondary battery consisting of positive electrode active material is economical, and has excellent rate maintenance factor and discharge capacity maintenance factor.    DETAILED DESCRIPTION - Manufacture of phosphoric acid compound involves preparing raw material containing 20-35 mol% lithium superoxide, 20-35 mol% phosphorus pentoxide, 35-55 mol% manganese dioxide, 0-10 mol% iron(III) oxide, 0-8 mol% cobalt(II, III) oxide, 0-15 mol% nickel oxide, and 0.05-10 mol% zinc oxide, calcium oxide, magnesium oxide, zirconium dioxide and/or titanium dioxide, heating the prepared raw material, obtaining molten material by melting, obtaining solidified material by cooling the molten material, pulverizing the solidified material and obtaining ground material, and obtaining particles containing crystals with olivine structure by heating the ground material. INDEPENDENT CLAIMS are included for the following:    (1) manufacture of positive electrode active material, which involves manufacturing phosphoric acid compound, and obtaining positive electrode material using the phosphoric acid compound;    (2) manufacture of secondary battery, which involves manufacturing positive electrode active material, and obtaining secondary battery using the positive electrode active material; and    (3) phosphoric acid compound, which comprises composition of formula: Li1+a(Mn1-(q+r)FeqMr)1-x+bXxPO4+c (I).    M=Co or Ni;    X=Mg, Zn, Ca, Zr or Ti;    a,b=-0.2 to 0.1;    q=0-0.3;    r=0-0.2;    x=0.001-0.2;and    q+r=0-0.35.