There are provided an etching mask which has a superior thermal imprinting characteristic and also a good anti-etching characteristic, a base material with the etching mask, a microfabricated product to which those etching mask and base material are applied, and a production method of the microfabricated product. The etching mask formed of a thermoplastic resin containing at least one kind of skeleton expressed by a chemical formula (1) or a chemical formula (2) in a main chain (R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 in the formulae (1), (2) can be different or same one another, each of which is a hydrogen atom, a deuterium atom, a hydrocarbon group having a carbon number of 1 to 15, a halogen atom, or a substituent group containing a hetero atom like oxygen or sulfur, and may form a ring structure one another. m and n are integers equal to or greater than 0).