PURPOSE: To provide the titled resin containing a specific amount of free phenols and little bicyclic component, having rapid curability and high crosslinkability and capable of giving a cured article having various excellent physical properties.

CONSTITUTION: A novolac phenolic resin having a number-average molecular weight (x) of 7004n1,500 (for the resin component excluding free phenols), a free phenol content of <1.0wt% and a bicyclic component content (y) of y≤-0.002x+4.4wt%. the resin can be produced by reacting a phenol comprising phenol and/or cresol with an aldehyde in the presence of a catalyst (e.g. oxalic acid). The reaction is carried out by supplying a precondensation reaction liquid into a pipe 4 furnished with a blade 5, mixing an inert gas such as nitrogen and/or steam to the liquid in the pipe 4, returning the mixture to a reaction apparatus 1, repeating the above procedure until a desired property is attained, and subjecting the reaction product to dehydrative condensation under reduced pressure.