A rotation angle sensing device that senses an angle error of an arbitrary section out of sections determined by multiple sensed portions rotating in synchronization with rotation of a crankshaft of an internal combustion engine by calculating a section parameter corresponding to a physical value of time necessary for rotation of the arbitrary section or a value equivalent to the time based on an output of a crank angle sensor sensing the arbitrary section when fuel cutting control for stopping fuel injection generating torque of the crankshaft is performed, the rotation angle sensing device being characterized by: an estimating device that estimates an inclination of an attenuation line, along which the physical value changes in proportion to a change of a rotation angle of the crankshaft, based on calculation values of the physical value related to rotation of a certain section, which is defined by two predetermined sensed portions located at a start and an end, respectively, of an integral multiple of one rotation of the crankshaft, wherein the inclination of the attenuation line is estimated as an attenuation degree of rotation speed of the crankshaft, which is attenuated due to the fuel cutting control; a calculating device that calculates the section parameters of multiple sections provided by dividing entire sections with the sensed portions, wherein the entire sections are defined by the integral multiple of the one rotation of the crankshaft; an entire section averaging device that calculates an average value of the section parameters of the entire sections as an entire section average value; and an error sensing device (S116, S118) that determines a reference value of the physical value of the arbitrary section based on the attenuation line while the entire section average value is used as intercept information of the attenuation line, and the error sensing device (S116, S118) senses the angle error of the arbitrary section based on a deviation of the section parameter of the arbitrary section from the reference value. an estimating device that estimates an inclination of an attenuation line, along which the physical value changes in proportion to a change of a rotation angle of the crankshaft, based on calculation values of the physical value related to rotation of a certain section, which is defined by two predetermined sensed portions located at a start and an end, respectively, of an integral multiple of one rotation of the crankshaft, wherein the inclination of the attenuation line is estimated as an attenuation degree of rotation speed of the crankshaft, which is attenuated due to the fuel cutting control; a calculating device that calculates the section parameters of multiple sections provided by dividing entire sections with the sensed portions, wherein the entire sections are defined by the integral multiple of the one rotation of the crankshaft; an entire section averaging device that calculates an average value of the section parameters of the entire sections as an entire section average value; and an error sensing device (S116, S118) that determines a reference value of the physical value of the arbitrary section based on the attenuation line while the entire section average value is used as intercept information of the attenuation line, and the error sensing device (S116, S118) senses the angle error of the arbitrary section based on a deviation of the section parameter of the arbitrary section from the reference value.