A high-ortho phenolic novolac resin having excellent curability, heat stability and flowability can be produced safely at low cost by a process which comprises reacting a phenol and an aldehyde at a temperature of more than 100.degree. C. with (A) a catalyst effective for the addition reaction selected from the salts of divalent metals in combination with (B) a catalyst effective for the condensation reaction, or comprises reacting a phenol and an aldehyde under reflux in the presence of the catalyst (A), adding an acid to adjust the pH to 1-5, removing water under reduced pressure and then subjecting the product to reaction at a temperature of more than 100.degree. C. This process enables the addition reaction and the condensation reaction to proceed with a good balance, can solve problems arising in the prior process such as gelation, low yield and the like, and can produce a high-ortho type phenolic novolac resin safely at low cost. Accordingly, this process is quite advantageous in industry.