To provide a new biadamantane carboxylic acid derivative excellent in solubility in a solvent and useful as a raw material for a functional material excellent in electrical characteristics, heat characteristics, etc.

This biadamantane phenol derivative is expressed by formula (1) [R1 to R6 are each H, a group expressed by formula (2) or another substituent, provided that at least one of R1 to R6 is a group expressed by formula (2)].