A circuit substrate comprising: a laminate substrate in which a plurality of conductive layers (40, 42, 44) and a plurality of insulating layers (30, 32, 34, 36, 38) are laminated; an antenna terminal that is formed on the laminate substrate; a transmit filter chip and a receive filter chip provided inside of the laminate substrate, and being electrically connected to the antenna terminal, the transmit filter chip having a transmit surface acoustic wave filter and being connected between a transmit node and an antenna node (Ant), the receive filter chip having a receive surface acoustic wave filter and being connected between a receive node (Rx) and an antenna node (Ant) and the transmit filter and the receive filter constituting a duplexer; an active component that is provided on a surface of the laminate substrate, is connected with the transmit filter chip and includes an amplifier, at least a part of the active component overlapping with a projected region (10c; 10d) that is a region of one of the transmit filter chip and the receive filter chip projected in a thickness direction of the laminate substrate, the transmit filter being configured to filter a signal amplified by the active component; and interconnection lines (40a, 50a) connecting the transmit filter chip and the active component, which interconnection lines (40a, 50a) include a first interconnection line extending in a face direction of the laminate substrate and a second interconnection line extending in the thickness direction of the laminate substrate; the first interconnection line being shorter than the second interconnection line. a laminate substrate in which a plurality of conductive layers (40, 42, 44) and a plurality of insulating layers (30, 32, 34, 36, 38) are laminated; an antenna terminal that is formed on the laminate substrate; a transmit filter chip and a receive filter chip provided inside of the laminate substrate, and being electrically connected to the antenna terminal, the transmit filter chip having a transmit surface acoustic wave filter and being connected between a transmit node and an antenna node (Ant), the receive filter chip having a receive surface acoustic wave filter and being connected between a receive node (Rx) and an antenna node (Ant) and the transmit filter and the receive filter constituting a duplexer; an active component that is provided on a surface of the laminate substrate, is connected with the transmit filter chip and includes an amplifier, at least a part of the active component overlapping with a projected region (10c; 10d) that is a region of one of the transmit filter chip and the receive filter chip projected in a thickness direction of the laminate substrate, the transmit filter being configured to filter a signal amplified by the active component; and interconnection lines (40a, 50a) connecting the transmit filter chip and the active component, which interconnection lines (40a, 50a) include a first interconnection line extending in a face direction of the laminate substrate and a second interconnection line extending in the thickness direction of the laminate substrate; the first interconnection line being shorter than the second interconnection line.