A semiconductor storage device of an embodiment includes a wiring layer M1 and a wiring layer M2. The wiring layer M1 includes a signal line through which a data signal is transferred, and a plurality of dummy patterns formed of a material same as a material of the signal line. The wiring layer M2 includes a voltage supply line through which voltage Vdd is supplied and another voltage supply line through which voltage Vss is supplied. Each of the dummy patterns is electrically connected with any one of the voltage supply lines. In a dummy pattern disposed adjacent to the signal line, a surface facing the signal line is constituted by a first surface positioned at a first distance to the signal line and a second surface positioned at a second distance to the signal line, the second distance being different from the first distance.