A solar cell comprising: a substrate having a first conductivity type; an emitter layer including a first impurity implanted into the substrate and the first impurity having a second conductivity type opposite the first conductivity type, doped therein, and positioned on one surface of the substrate so that the emitter layer is formed on the one surface of the substrate; a plurality of front finger lines connected with the emitter layer and extending in a first direction to be parallel to each other on the one surface of the substrate; a back surface field positioned on the other surface of the substrate facing the one surface of the substrate, and including a second impurity having the first conductivity type doped therein; and a plurality of rear finger lines connected with the back surface field and extending in the first direction to be parallel to each other on the other surface of the substrate, and wherein the substrate is n-type and an antireflective layer entirely covers the other surface of the substrate except for the plurality of rear finger lines, the antireflective layer also serving as a passivation layer, wherein the emitter layer includes first areas in contact with the plurality of front finger lines and second areas positioned between the plurality of front finger lines and having a lower doping concentration than that of the first areas, wherein the back surface field includes areas in contact with the plurality of rear finger lines, and wherein the number of the plurality of rear finger lines positioned on the other surface of the substrate and the number of the plurality of front finger lines positioned on the one surface of the substrate are different; wherein a ratio of a distance between two adjacent front finger lines among the plurality of front finger lines to a distance between two adjacent rear finger lines among the plurality of rear finger lines is greater than 1 and smaller than 5, and wherein the back surface field is separated by a distance or gap from each edge of the other surface of the substrate. a substrate having a first conductivity type; an emitter layer including a first impurity implanted into the substrate and the first impurity having a second conductivity type opposite the first conductivity type, doped therein, and positioned on one surface of the substrate so that the emitter layer is formed on the one surface of the substrate; a plurality of front finger lines connected with the emitter layer and extending in a first direction to be parallel to each other on the one surface of the substrate; a back surface field positioned on the other surface of the substrate facing the one surface of the substrate, and including a second impurity having the first conductivity type doped therein; and a plurality of rear finger lines connected with the back surface field and extending in the first direction to be parallel to each other on the other surface of the substrate, and wherein the substrate is n-type and an antireflective layer entirely covers the other surface of the substrate except for the plurality of rear finger lines, the antireflective layer also serving as a passivation layer, wherein the emitter layer includes first areas in contact with the plurality of front finger lines and second areas positioned between the plurality of front finger lines and having a lower doping concentration than that of the first areas, wherein the back surface field includes areas in contact with the plurality of rear finger lines, and wherein the number of the plurality of rear finger lines positioned on the other surface of the substrate and the number of the plurality of front finger lines positioned on the one surface of the substrate are different; wherein a ratio of a distance between two adjacent front finger lines among the plurality of front finger lines to a distance between two adjacent rear finger lines among the plurality of rear finger lines is greater than 1 and smaller than 5, and wherein the back surface field is separated by a distance or gap from each edge of the other surface of the substrate.