The Fostering Network said the shortage was particularly acute for carers of teenagers, children with disabilities and siblings.
They say that without enough families, children find themselves living a long way from family, school and friends, being split up from brothers and sisters or being placed with a foster carer who does not have the ideal skills and experience to meet their specific needs.
The charity said the figure matched last year's recruitment target but was a rise on previous years.
Sara Lurie, director of the Fostering Network Scotland, said:"Fostering can be a challenging job and when the match between foster family and child is not ideal, it becomes even more difficult. Too many fostering relationships break down as a result.
"A wider pool of foster carers makes it more likely that fostering services can find the right foster home for each child, first time.
"We urgently need people who believe that they have the right skills and qualities to foster to come forward and make a long-lasting positive difference to the life of a child.
"In particular, foster carers are needed to provide homes for teenagers and children with disabilities, and to help sibling groups stay together."
It comes after reforms were announced to allow young people in Scotland to remain in care until the age of 21. Campaigners have said it will make Scotland a "world leader" in the field.