An operation input detection device includes an operation input detection unit, a change amount accumulation unit, a section variation amount calculating unit, and a noise determination unit. The operation input detection unit detects an operation input on an operation input unit based on a sensor output of a capacitance sensor. The change amount accumulation unit accumulates a change amount of the sensor output in a determination section. The change amount of the sensor output is a difference of a detection value of the sensor output detected as each sampling timing from a previous value of the sensor output. The section variation amount calculating unit calculates a section variation amount of the sensor output.