The woman was locked away close to the town of Jonkoping in the south of Sweden, police spokesman Nils-Erik Eriksson said.
He declined to give further details, saying the man would soon be facing charges for illegally detaining the woman.
The woman, who suffered from multiple sclerosis, a disease which affects the nervous system and reduces physical mobility, weighed between 35 and 40 kilos and was admitted to hospital, Swedish news agency TT said.
TT also said that she had been locked up for nine years.