A wireless power transmission device (S1; S2; S3) for wirelessly transmitting power comprising: - a power source, - a power feeding coil unit (Ltu1; Ltu2; Ltu3) for wirelessly feeding power, - a power receiving coil (Lr) that is arranged to face the power feeding coil unit during power feeding, and - an inverter provided for converting input direct current power supplied from the power source into alternating current power and for supplying the alternating current power to the power feeding coil unit (Ltu1; Ltu2; Ltu3), wherein the power feeding coil unit (Ltu1; Ltu2; Ltu3), comprises: a power feeding coil (Lta, Ltb); and an auxiliary coil (Lca, Lcb), wherein the auxiliary coil (Lca, Lcb) is arranged such that the magnetic flux generated by the auxiliary coil (Lca, Lcb) does not cancel a magnetic flux that is generated by the power feeding coil (Lta, Ltb) and is interlinking with the power receiving coil (Lr) during power feeding, wherein an axial direction of the auxiliary coil (Lca, Lcb) is nonparallel to an opposing direction of the power feeding coil (Lta, Ltb) and the power receiving coil (Lr), and a direction of circulation of a magnetic flux generated by the auxiliary coil (Lca, Lcb) is opposite to a direction of circulation of a magnetic flux generated by the power feeding coil (Lta, Ltb), wherein the auxiliary coil (Lca, Lcb) is located on the opposite to a side of the power feeding coil (Lta, Ltb) facing the power receiving coil (Lr), wherein the auxiliary coil (Lca, Lcb) is arranged so that part or all of the auxiliary coil (Lca, Lcb) overlaps the power feeding coil (Lta, Ltb) when viewed from the opposing direction of the power feeding coil (Lta, Ltb) and the power receiving coil (Lr). - a power source, - a power feeding coil unit (Ltu1; Ltu2; Ltu3) for wirelessly feeding power, - a power receiving coil (Lr) that is arranged to face the power feeding coil unit during power feeding, and - an inverter provided for converting input direct current power supplied from the power source into alternating current power and for supplying the alternating current power to the power feeding coil unit (Ltu1; Ltu2; Ltu3), wherein the power feeding coil unit (Ltu1; Ltu2; Ltu3), comprises: a power feeding coil (Lta, Ltb); and an auxiliary coil (Lca, Lcb), wherein the auxiliary coil (Lca, Lcb) is arranged such that the magnetic flux generated by the auxiliary coil (Lca, Lcb) does not cancel a magnetic flux that is generated by the power feeding coil (Lta, Ltb) and is interlinking with the power receiving coil (Lr) during power feeding, wherein an axial direction of the auxiliary coil (Lca, Lcb) is nonparallel to an opposing direction of the power feeding coil (Lta, Ltb) and the power receiving coil (Lr), and a direction of circulation of a magnetic flux generated by the auxiliary coil (Lca, Lcb) is opposite to a direction of circulation of a magnetic flux generated by the power feeding coil (Lta, Ltb), wherein the auxiliary coil (Lca, Lcb) is located on the opposite to a side of the power feeding coil (Lta, Ltb) facing the power receiving coil (Lr), wherein the auxiliary coil (Lca, Lcb) is arranged so that part or all of the auxiliary coil (Lca, Lcb) overlaps the power feeding coil (Lta, Ltb) when viewed from the opposing direction of the power feeding coil (Lta, Ltb) and the power receiving coil (Lr). a power feeding coil (Lta, Ltb); and an auxiliary coil (Lca, Lcb), wherein the auxiliary coil (Lca, Lcb) is arranged such that the magnetic flux generated by the auxiliary coil (Lca, Lcb) does not cancel a magnetic flux that is generated by the power feeding coil (Lta, Ltb) and is interlinking with the power receiving coil (Lr) during power feeding, wherein an axial direction of the auxiliary coil (Lca, Lcb) is nonparallel to an opposing direction of the power feeding coil (Lta, Ltb) and the power receiving coil (Lr), and a direction of circulation of a magnetic flux generated by the auxiliary coil (Lca, Lcb) is opposite to a direction of circulation of a magnetic flux generated by the power feeding coil (Lta, Ltb), wherein the auxiliary coil (Lca, Lcb) is located on the opposite to a side of the power feeding coil (Lta, Ltb) facing the power receiving coil (Lr), wherein the auxiliary coil (Lca, Lcb) is arranged so that part or all of the auxiliary coil (Lca, Lcb) overlaps the power feeding coil (Lta, Ltb) when viewed from the opposing direction of the power feeding coil (Lta, Ltb) and the power receiving coil (Lr).