An image sensor comprising: a plurality of microlenses; and a pixel array having, with respect to each of the microlenses, a pair of first regions formed at a first depth from a surface on which light is incident, a pair of second regions formed at a second depth deeper than the first depth, and a plurality of connecting regions that connects the pair of first regions and the pair of second regions, respectively, wherein a direction of arranging the pair of second regions corresponding to each microlens is a first direction, and a direction of arranging the pair of first regions is either the first direction or a second direction which is orthogonal to the first direction, wherein the first regions generate charge by performing photoelectric conversion on incident light, and the second regions accumulate the charge generated in the first regions via the connecting regions, wherein the pixel array further includes conversion means configured to convert charge into voltage, and transfer means, which is connected to each of the second regions, configured to transfer the charge accumulated in the second regions to the conversion means, characterized in that a length of each of the second regions in the depth direction in a first partial region of the second region is shorter than a length of said second region in the depth direction in a second partial region of the second region, or an impurity concentration in the first partial region is lower than an impurity concentration in the second partial region, wherein the first partial region is located farther from the transfer means than the second partial region. a plurality of microlenses; and a pixel array having, with respect to each of the microlenses, a pair of first regions formed at a first depth from a surface on which light is incident, a pair of second regions formed at a second depth deeper than the first depth, and a plurality of connecting regions that connects the pair of first regions and the pair of second regions, respectively, a pair of first regions formed at a first depth from a surface on which light is incident, a pair of second regions formed at a second depth deeper than the first depth, and a plurality of connecting regions that connects the pair of first regions and the pair of second regions, respectively, wherein a direction of arranging the pair of second regions corresponding to each microlens is a first direction, and a direction of arranging the pair of first regions is either the first direction or a second direction which is orthogonal to the first direction, wherein the first regions generate charge by performing photoelectric conversion on incident light, and the second regions accumulate the charge generated in the first regions via the connecting regions, wherein the pixel array further includes conversion means configured to convert charge into voltage, and transfer means, which is connected to each of the second regions, configured to transfer the charge accumulated in the second regions to the conversion means, a length of each of the second regions in the depth direction in a first partial region of the second region is shorter than a length of said second region in the depth direction in a second partial region of the second region, or an impurity concentration in the first partial region is lower than an impurity concentration in the second partial region, wherein the first partial region is located farther from the transfer means than the second partial region.