A method for manufacturing a semiconductor IC-embedded substrate, comprising: a first step for inserting, between first and second resin layers (111, 112), a semiconductor IC in which conductive protrusions are provided to a principal surface; a second step for causing the conductive protrusions of the semiconductor IC to protrude from a first surface of the first resin layer by reducing the overall thickness of the first resin layer after the first step, a protruding amount of the conductive protrusions being set to 0.1 to 20 μm; and a third step for forming a wiring pattern on the first surface of the first resin layer wherein the first step includes: a step for stacking the second resin layer and the semiconductor IC so that a first surface of the second resin layer and a back surface of the semiconductor IC face each other, and a subsequent step for stacking the first resin layer and the semiconductor IC so the a second surface of the first resin layer and the principal surface of the semiconductor IC face each other. wherein the first step stacks the second resign layer and the semiconductor IC so that the second and first resin layer (111, 112) are closely attached to one another, wherein the second step is performed by reducing the overall thickness by wet blasting the first surface of the first resin layer. a first step for inserting, between first and second resin layers (111, 112), a semiconductor IC in which conductive protrusions are provided to a principal surface; a second step for causing the conductive protrusions of the semiconductor IC to protrude from a first surface of the first resin layer by reducing the overall thickness of the first resin layer after the first step, a protruding amount of the conductive protrusions being set to 0.1 to 20 μm; and a third step for forming a wiring pattern on the first surface of the first resin layer wherein the first step includes: a step for stacking the second resin layer and the semiconductor IC so that a first surface of the second resin layer and a back surface of the semiconductor IC face each other, and a subsequent step for stacking the first resin layer and the semiconductor IC so the a second surface of the first resin layer and the principal surface of the semiconductor IC face each other. wherein the first step stacks the second resign layer and the semiconductor IC so that the second and first resin layer (111, 112) are closely attached to one another, wherein the second step is performed by reducing the overall thickness by wet blasting the first surface of the first resin layer. a step for stacking the second resin layer and the semiconductor IC so that a first surface of the second resin layer and a back surface of the semiconductor IC face each other, and a subsequent step for stacking the first resin layer and the semiconductor IC so the a second surface of the first resin layer and the principal surface of the semiconductor IC face each other. wherein the first step stacks the second resign layer and the semiconductor IC so that the second and first resin layer (111, 112) are closely attached to one another, wherein the second step is performed by reducing the overall thickness by wet blasting the first surface of the first resin layer.