This paper addresses the boundary stabilization problem of one-dimensional linear parabolic systems with input delay. Especially, the case of Neumann boundary control is studied. The purpose is to derive the stabilizing controller of predictor type in a Hilbert space, by using a backstepping method combined with the semigroup theory. The use of the semigroup theory makes the proof of continuity of the inverse transformation easy. Also, it is shown that the implementation of the abstract controller is feasible by using a finite number of eigenvalues and eigenfunctions of the system operator.