The printed wiring board has a conductor of signal line 41 and two conductive lines 42 on one face of the first insulating layer 10 covered by a second insulating layer 20, while having a ground layer of the ground 30 potential on the opposite face thereof, when the dielectric tangent A of the second insulating layer (insulating layer A) 20 is larger than the dielectric tangent B of the first insulating layer (insulating layer B) 10, Relational Expression 1: (relative permittivity B)·(width (W41) of signal line(s) 41)/(thickness (T10) of first insulating layer (insulating layer B) 10)>(relative permittivity A)·{(thickness (T41) of signal line(s) 41)/(distance (S1) between signal line(s) 41 and one conductive line 42a)+(thickness (T41) of signal line(s) 41)/(distance (S2) between signal line(s) 41 and other conductive line 42b)+(thickness (T41) of signal lines 41)/(distance (S3) between pair of signal lines (41a and 41b)·2} is satisfied.