A man accused of operating the Instagram account and a 22-year-old mother who allegedly put her child up for adoption were both arrested last week, East Java police spokesperson Frans Barung Mangera told AFP.
Police said the mother wanted to sell her 11-month-old third child because she was in debt.
"According to (the mother's) statement, the baby was the result of an affair," said Sudamiran, who like many Indonesians has only one name.
Giving birth out of wedlock is highly stigmatised in Indonesia, the world's largest Muslim-majority country, and single mothers are sometimes shunned by their family.
The Instagram account's operator was to have pocketed Rp 2.5 million from the baby's sale, police said.
The account was still active on Friday with more than 760 followers.
It had posted dozens of black and white photos of ultrasounds and mothers whose faces were partially obscured to hide their identity.
The page claims to offer "family solutions" and lists the personal details of women offering to sell their child, including their age, religion, stage of pregnancy and health.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)