PURPOSE: To realize a semiconductor device cross section observing method wherein a semiconductor device can be surely and quickly cut so as to enable its cross section at an optional point to be surely observed in order that it can be judged that manufacturing conditions are set adequate or not in a semiconductor device manufacturing process.

CONSTITUTION: A chip 1 is bonded to a glass plate 4 with transparent adhesive agent making its surface 1a confront the plate 4, and the peripheries of the chip 1 and the glass plate 4 are removed viewing the surface 1a through the glass plate 4, whereby the objective cross section of the chip 1 to observe is exposed, and the transparent adhesive agent is melted or dissolved to separate the chip 1 from the glass plate 4, and then the cross section of the chip 1 is observed.