18世紀半ばから19世紀前半にかけて80年余りの間における出雲国神門郡102村の人口の増加と性比の上昇（男性化）およびその後の低下について，おもに男女別の人口増加率および家数と家あたり人数の増加率を時間的・空間的に観察することにより研究した。18世紀においては女の人口増加率が負か極めて小さいこと，また，1754年の村別の家あたり人数と人口性比と間には負の相関（－0.40）があることから女児のマビキの存在を推定し，また，その関係が1824年にはみられなくなったことから19世紀前半にかけてマビキの程度が緩和されたことを推定した。沿海，中間，山間の3地域別の人口性比を1863年の石見銀山領におけるものと対比させ，山間の人口性比の高さが，出生性比によるものでなく17歳以上の人口性比によることから，もっぱら女性の死亡率の高さによってもたらされていることを推定した。死亡率が相対的に高かった山間においてもその低下が進み，女性人口増加率が男のものより高くなることによって1830年代に人口性比が低下に転換したことを明らかにした。3地域別および村別に人口増加率に対して，家数増加率，家あたり人数増加率がどのように貢献したかを要因分解すると，人口増加率はもっぱら家数増加率によってもたらされ，家あたり人数増加率はむしろ負に働いた。しかし，その村別の値の相関係数をみると，人口増加率と家あたり人数増加率との相関は正，つまり，家あたり人数の減少の小さい村ほど人口増加率が大きいことを示している。これは諏訪の例（速水1973）と異なり，家数の増大の制約がより弱いことを示していると考えられ，神門郡の人口増加が主として家数の増加によってもたらされ，家数増加が家あたり人数をより強く減少させるほどの強さであったのであろう。

Increase with rising sex ratio of the population in Kando county along Japan Sea coast in western part of Honshu Island from 1754 to 1837 was investigated by the population records by village made and preserved by the head of the county, Yamamoto family.
The practice of mabiki (abortion and infanticide) of mostly female offspring in the 18th century was estimated by the negative correlation (-0.40) between the population sex ratio and the size of the household by village in 1754 but it was far weakened in 19th century indicated by the disappearance of the correlation in 1837. The practice of it was also corroborated by the negative or virtually zero growth of the female population comparing with positive growth rate (0.1 %) of male counterpart from 1754 to 1791.
The county was divided into three districts by geographical condition: sea coast, middle, mountainous. As the highest sex ratio of the mountainous district was accounted for not by the sex ratio under 16 years old but by that over 16 years old, it was estimated to be caused not by the sex ratio at birth but by the higher mortality of women over 16 years old. Therefore, it was clarified that the decline of mortality of women raised the female population growth rate and lowered the population sex ratio since 1833.
The population growth rates of villages from 1754 to 1837 were decomposed into the growth rates of household number and the growth rates of household members. The decomposition revealed that the population growth rates were mostly accounted for by the growth rates of household number and that the growth rates of household members affected negatively to the population growth. Nonetheless, the correlation between the population growth rates of villages and the growth rates of household members was positive, which means that the less decrease in the household members, the more increase in the population growth rates. Thus it was concluded that the increase of households accompanying the population growth was so marked that it decreased the household members.