A piezoelectric substrate attachment structure including a cable-shaped piezoelectric substrate, a press section provided adjacent to the piezoelectric substrate and pressed from an opposite side from the piezoelectric substrate, and a base section provided adjacent to the piezoelectric substrate on an opposite side from the press section. A ratio Eb/Ea of a Young's modulus Eb of the base section to a Young's modulus Ea of the press section being 10−1 or lower.