A negative pressure abnormality detection apparatus includes a negative pressure sensor to output a signal representing negative pressure in a negative pressure chamber of a brake booster into which intake negative pressure of an intake manifold generated by rotation of an engine is introduced; a negative pressure detection unit to detect the negative pressure based on the signal; an abnormality determination unit to determine whether an abnormality occurs with the negative pressure sensor, based on whether the negative pressure is shifted toward atmospheric or vacuum pressure relative to a threshold, when a state continues for a predetermined time or longer during which the engine rotates and a negative-pressure-expending braking operation is not performed; and a threshold change unit to change the threshold depending on opening of a throttle valve in an intake pipe connected with the intake manifold, while the state continues.