To prevent a product carton or the like without thermosetting adhesive normally applied from being carried by sensing whether there is the adhesive ejected from a thermosetting adhesive ejecting member on a side of a passage of the adhesive and determining whether the adhesive has been applied on a box based on the sensing signal.

A product carton K is transferred on a conveyer V, and a hot melt M' is ejected onto its upper face in strings from an ejection port (g) of a melt gun G. A frame 2 is horizontally bridged on an upstream of the position where the melt gun G is installed and lower than the frame 1 of the melt gun G1 and orthogonal to the transfer direction of the conveyer belt V. Photoelectric sensors S1 to S4 are placed oppositely to respective passages of four lines of the hot melt M' on the frame 2 for detecting whether the hot melt M' has been ejected. A control part determines whether application is normal based on sensing the signals of the photoelectric sensors S1 to S4, and at the time of abnormality detected, an alarm is issued and a transfer is stopped.