An intake manifold incorporating an intercooler configured to cool intake air entering an engine, wherein the intake manifold comprises: an opening portion through which a core of the intercooler is inserted thereinto; a flat shaped flange that extends from an end face of the core that is inserted into the intake manifold through the opening portion, and that is attached to an external surface of an edge portion of the opening portion; a top plate that is formed separately from the flange and that fixes the flange to the external surface of the edge portion; an EGR passage that is disposed along an internal surface of the edge portion in a position that lies adjacent to the core so as to constitute a flow path for an EGR gas that returns from an exhaust system to an intake system of the engine; a first protuberant portion that protrudes towards an inside of the EGR passage so as to generate turbulence in the flow of EGR gas; a second protuberant portion that protrudes towards an inside of an intake passage through which the intake air flows so as to generate turbulence in the flow of intake air, and a fixing member that fixes the top plate and the flange to the intake manifold, wherein the top plate has a shape that overlaps the EGR passage when seen from an inserting direction of the core, the top plate is disposed so as to partially cover the EGR passage, the intake manifold is characterized in that: a wall surface of a wall disposed between the EGR passage and an intake passage in a center portion of the intake manifold is inclined with respect to an insertion direction of the fixing member, the wall surface includes a cylindrical boss formed around a hole into which the fixing member is inserted, and the first and second protuberant portions (6, 7) are parts of the cylindrical boss. an opening portion through which a core of the intercooler is inserted thereinto; a flat shaped flange that extends from an end face of the core that is inserted into the intake manifold through the opening portion, and that is attached to an external surface of an edge portion of the opening portion; a top plate that is formed separately from the flange and that fixes the flange to the external surface of the edge portion; an EGR passage that is disposed along an internal surface of the edge portion in a position that lies adjacent to the core so as to constitute a flow path for an EGR gas that returns from an exhaust system to an intake system of the engine; a first protuberant portion that protrudes towards an inside of the EGR passage so as to generate turbulence in the flow of EGR gas; a second protuberant portion that protrudes towards an inside of an intake passage through which the intake air flows so as to generate turbulence in the flow of intake air, and a fixing member that fixes the top plate and the flange to the intake manifold, wherein the top plate has a shape that overlaps the EGR passage when seen from an inserting direction of the core, the top plate is disposed so as to partially cover the EGR passage, the intake manifold is characterized in that: a wall surface of a wall disposed between the EGR passage and an intake passage in a center portion of the intake manifold is inclined with respect to an insertion direction of the fixing member, the wall surface includes a cylindrical boss formed around a hole into which the fixing member is inserted, and the first and second protuberant portions (6, 7) are parts of the cylindrical boss. a wall surface of a wall disposed between the EGR passage and an intake passage in a center portion of the intake manifold is inclined with respect to an insertion direction of the fixing member, the wall surface includes a cylindrical boss formed around a hole into which the fixing member is inserted, and the first and second protuberant portions (6, 7) are parts of the cylindrical boss.