To very simply and surely connect and release boots and a binding by providing a boot engagement part supported by a forward extended part formed on a back support and a connecting means for removably connecting the forward extended part and a base plate to each other when the forward extended part is pressed down.

When as shown in the drawing, with a back support 6 inclined backward, a boot 2 is pressed onto a binding 1 in such a manner that a forward pin 17 enters a forward hook 4, simultaneously a forward extended part 7 of the back support 6 is pressed down through a stepping plate 10 by the lower surface of the boot 2. A rotary hook 14 enters an engagement recessed part 12, so that the forward extended part 7 is fixed to the base plate 3, a rear pin 18 of the boot 2 is engaged with a rear hook 8 of the forward extended part 7, and further the back support 6 is erected to come into contact with the back part of the boot 2, so that the boot 2 is completely fixed to the binding 1.