By using the dielectric relaxation method, we studied molecular dynamics of alpha-tetralone. Our purpose was to reveal the molecular origin of secondary processes observed for this very simple-structured molecule. To this end, we carried out dielectric measurements at both ambient and elevated pressure of neat alpha-tetralone and in mixture with oligostyrene. By means of both experimental observations and theoretical calculations, we proved that one of the secondary relaxations has the intramolecular origin, while the other is undoubtedly the intermolecular process called Johari-Goldstein relaxation characteristic of the glassy state.