To estimate the number of layers required for drawing wirings out of a BGA
component at a high speed. A layer number estimation device includes: a
bottleneck line detection means, a wiring layer adding means, and a
repeating means. The bottleneck line detection means detects a line as a
bottleneck line, among a plurality of lines formed by connecting
electrodes, where the number of electrodes located nearer the center side
than the lines is greater comparing with the number of wirings capable of
passing through the lines. The wiring layer adding means disposes
electrodes, among the electrodes located nearer the center side than the
bottleneck line, which remain after subtracting the number of wirings
capable of passing through the bottleneck line, on the next wiring layer
with vias. The repeating means causes the bottleneck line detection means
and the wiring layer adding means to be executed to the next wiring
layer.