The structures of 1-naphthol/alcohol clusters, 1-NpOH(ROH)(n) (n = 1-3; ROH = MeOH, EtOH, and t-BuOH), have been investigated by resonant two-photon ionization (R2PI) spectroscopy and ion-detected IR dip spectroscopy. On the basis of the calculated spectra obtained by ab initio MO calculations, the spectra of 1-NpOH(MeOH)(n) was analyzed. The analysis elucidated that 1-NpOH(MeOH)(2,3) was a ring structure. From a similarity of the spectral pattern, the structures of 1-NpOH(EtOH)(n) and 1-NpOH(t-BuOH)(n) were also determined to be a ring conformation. From a frequency shift of the hydrogen-bonded OH stretching vibration, the hydrogen bonding is weakened by a steric hindrance due to an alkyl group of ROH. The difference in the solvation mechanism between 1-NpOH(MeOH)(n) and 1-NpOH(H2O)(n) is discussed.