The list would contain the details of sex offenders and child traffickers with offenders registered "forever", Spain's Ministry of Health, Social Services and Equality announced recently.
People on the list could be banned from professions involving "regular contact with children", the ministry added.
The register is one of those proposals in Spain's new draft Child Protection Bill, approved by ministers on Friday.
If the law is passed in parliament, Spain will have a similar system to the US and the UK where sex offenders details are kept on file.
But Spain's El País newspaper have criticized the draft for a lack of detail.
Under the proposed legislation, all institutions and firms employing people who work with children would have to ensure they haven't committed a crime against children. It is unclear, however, how that would work in practice.
In other countries, employers are obliged to request the criminal records of children working with them, but that is not the case in Spain, the daily said.
There was also a lack of clarity about which professions were affected, El País added.
One lawyer consulted by the paper noted crimes were removed from a person's criminal record after a given period: this mean Spain's penal code would need to be changed so that crimes against minors were not deleted.
Another expert said the legislation was "notoriously" vague and pointed out all criminals in Spain were legally entitled to reenter society fully "independent of their crime".