To obtain a helmet having a head band whose belt-like ends can be connected to each other in a substantially unseparable state by fitting the T-shaped projection of the belt-like end of the head band into the long hole of the other belt-like end and further fitting the projections of the belt-like end into penetrated holes.

The head band 3 in the helmet has left and right belt-like ends 32L, 32R. Either of the left and right belt-like ends 32L, 32R has a T-shaped projection 34 projected in a T-shaped cross section and further projections 36 at places near to the T-shaped projection 34. The other belt-like end has a longitudinally extended long hole 35 and plural penetrated holes 37 formed along the long hole 35. The T-shaped projection 34 is fit into the long hole 35, and the projections are also fit into the penetrated holes 37.