When package circuit boards are formed by dicing a circuit board sheet with a core substrate that conducts electricity, conductive material is not exposed from the outer side surfaces of the package circuit boards, thereby preventing electrical shorting of the package circuit boards. A method of dicing a circuit board sheet includes: a step of forming a circuit board sheet by forming a core portion that includes a conductive material and providing a wiring layer on the surface of the core portion; a step of forming concave channels in a thickness direction of the circuit board sheet from one surface of the circuit board sheet so as to pass through at least the core portion; a step of forming an insulating cover layer on a surface of the wiring layer and inside the concave channels; and a step of dicing the circuit board sheet within widths of the concave channels with positions of the concave channels as dicing positions.