Photosensitive polyimides have been used to form thermally and mechanically stable fine patterns utilized for such as buffer-coat layers and inter-layer dielectrics in electronic devices. Conventional photosensitive polyimides usually contain poly(amic acid)s as polyimide precursors or functionalized polyimides as their polymer component. Here, we report a novel design for preparation of photosensitive polyimides, reaction development patterning(RDP). RDP utilizes nucleophilic acyl substitution reaction of nucleophiles in developer with imide groups in polyimides as the key reaction of pattern formation, and therefore, no introduction of specific functional groups into polyimide framework is needed. In addition, RDP can afford photosensitivity to engineering plastics having carboxylic-acid-derivative linkages other than polyimide. We have developed both positive- and negative-tone RDPs. Positive-tone RDP utilizes main-chain scission of engineering plastics by amines in developer for pattern formation. Negative-tone RDP realizes higher sensitivity with smaller amount of photosensitive agent than positive-tone RDP. Application of industrially-used alkaline developer to negative-tone RDP is also achieved. Further reduction of the amount of photosensitive agent with increasing sensitivity is examined by introduction of chemical amplification mechanism to RDP.