an image recording apparatus inhibiting recording of abnormally - fed sheets includes conveying structure for conveying a sheet along a predetermined conveying path . detection circuitry is provided for detecting a dimension of a sheet being fed by the conveying structure . a memory is provided for storing a reference value corresponding to a dimension of a sample sheet detected by the detection circuitry . judging circuitry is provided for judging the abnormal feeding of a sheet by comparing the dimension of the sheet detected by the detection circuitry with the reference value stored in the memory . reading circuitry is provided for reading information from the sheet , and a control circuit is provided for inhibiting the reading of the information from a sheet which is judged to have been abnormally fed , but for allowing the reading of the information from a sheet which has been judged to have been normally fed . preferably , the detected dimension is the thickness and / or the length of the sheet .