PROBLEM TO BE SOLVED: To improve accuracy of detecting fuel alcohol concentration when fuel temperature significantly changes.;SOLUTION: An alcohol concentration detection apparatus is applied to a capacitive concentration sensor. The alcohol concentration detection apparatus calculates fuel alcohol concentration at the time of a first point of time or a concentration correlation value correlated therewith. In calculating the concentration correlation value, an output of the concentration sensor and a fuel temperature near a sensing part of the concentration sensor or a temperature correlation value having a correlation with the fuel temperature are obtained. When the amount of change in temperature correlation value in a predetermined period immediately before the first point of time is larger than a first reference value, the fuel alcohol concentration calculated according to the output of the concentration sensor and obtained before the amount of change for each predetermined period is larger than the first reference value or the concentration correlation value correlated therewith is set to the concentration correlation value at the first point of time.;COPYRIGHT: (C)2015,JPO&INPIT
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