Five constituents were isolated from the stem of Acanthopanax senticosus. Their structures were elucidated as (-)-sesamin (1), iso-fraxidin (2), 5-hydroxymethylfurfural (3), syringin (4) and acanthoside D (5) by spectral analysis. Among these compounds, 5-hydroxymethylfurfural (3) was isolated for the first time from this plant.