Magnetic-field-angle-resolved specific heat and magnetization measurements were conducted on a ferromagnetic superconductor UCoGe with remarkable anisotropic upper critical field . Although reaches a high magnetic field () along the axis, it is small () when a magnetic field is applied along the magnetic easy axis. This study indicates that the specific heat is abruptly suppressed when the magnetic field is applied toward the axis from the and axes in the ferromagnetic state. The field response of density of states (DOS) is anisotropic, relative to the axis, and its angle dependence is slightly singular. The Ising-type magnetic anisotropy of the ferromagnetic state is dominant even in the anisotropic reinforced superconducting state. These facts indicate that the suppression of DOS may closely relate to the superconducting state. We theoretically analyze these findings together with URhGe and by highlighting the common and distinctive features among three compounds.