An apparatus and method for controlling a converter are provided. The apparatus includes a battery and a sensor configured to sense the battery to generate sensor state of battery information. A converter controller is configured to acquire the sensor state of battery information and vehicle state information received from a vehicle controller to calculate calibrated state of battery information based on whether a correction execution condition on the sensor state of battery information is satisfied. In addition, the converter controller uses the calibrated state of battery information and the sensor state of battery information to calculate an error correction value and uses the error correction value to calculate actual state of battery information. A converter is then configured to supply power to the battery based on the sensor state of battery information or the actual state of battery information.