Provided is a nonvolatile storage device (200) capable of stably operating without increasing a size of a selection transistor included in each of memory cells. The nonvolatile storage device (200) includes: a semiconductor substrate (301) which has a P-type well (301a) of a first conductivity type; a memory cell array (202) which includes memory cells (M11) or the like each of which includes a variable resistance element (R11) and a transistor (N11) that are formed above the semiconductor substrate (301) and connected in series; and a substrate bias circuit (220) which applies, to the P-type well (301a), a bias voltage in a forward direction with respect to a source and a drain of the transistor (N11), when a voltage pulse for writing is applied to the variable resistance element (R11) included in the selected memory cell (M11) or the like.