An analyzer (A) includes a measurer (42) for measuring an electro-physical quantity of a sample, and an acceleration measurer (43) for computing the acceleration of change of the electro-physical quantity such as a current measured by the measurer (42). The fail determination as to whether or not a predetermined condition necessary for performing analysis of the sample is satisfied is made based on the acceleration computed by the acceleration measurer (43). As a result, the fail determination in the analysis process of the sample can be performed accurately.