To provide a box type safety cap of a T-razor with a simple constitution having an universal type of a head part, is widely applicable to T-razors having the head part of various types and is safely, surely and freely attachable to the T-razor.

This box type safety cap 50 houses the head part 61 of the T-razor 60 by inserting the box type safety cap 50 of the T-razor 60 opened at one end in its longitudinal direction by inserting the box type safety cap 50 into the T-razor 60 from a forward direction while relatively moving the T-razor 60 and the box type safety cap 50. A bottom plate part 20 of the box type safety cap 50 has a first notch 21 which is formed on the central of the longitudinal direction, opens to the opening side and is inserted with a handle 62 of the T-razor 60, projections 23 and 23 which are respectively projectingly disposed on both side walls of the first notch 21 and second notches 22 and 22 which are respectively formed on both sides of the first notch 21, open to the opening side and impart elasticity to the respective projections 23 and 23. The bottom plate part freely attachably and detachably detains the handle 62 of the T-razor 60.