In cases of higher education, legalization is required.

Legalization is carried out by:

1) Polish consul in the country where diploma was issued or in the country in which educational system a university operates;

If a diploma was issued by a country – party to the Hague Convention of 5th October 1961 abolishing the Requirement for Legalisation for Foreign Public Documents, a diploma must be submited along with the Apostille attached to it. Check if the country in which the certificate was issued is a party to the Hague Convention:

https://www.hcch.net/en/states/hcch-members