Provided is a positive photoresist composition containing a cresol novolac resin (A) manufactured using m-cresol, p-cresol, and formaldehyde as essential raw materials and a novolac phenolic resin (B) manufactured using o-cresol, resorcinol, and formaldehyde as essential raw materials. This positive photoresist composition has high sensitivity and high heat resistance at the same time, which have so far been difficult to achieve at the same time, at a higher level and is suitable for use as a resist in, for example, the manufacture of semiconductor devices such as ICs and LSIs, which have required formation of finer patterns with the increasing packing density in recent years, the manufacture of displays such as LCDs, and the manufacture of printing plates.