For the acquisition of the alpha particle distribution, two-dimensional photodetectors combined with a scintillator plate have been developed over the past years. The individual energies of the alpha-emitting radionuclides should be identified for the quantitative analysis. This can be done by the spectrometric method after energy and efficiency calibrations. In order to calibrate energy and efficiency, multi-peak calibration methods using a number of standard sources are widely used in alpha spectroscopy. In this study, we proposed an energy and efficiency calibration method with a single standard source and characterized an alpha imaging detector. We obtained fitting coefficients for the energy calibration curve using each channel of the peak from the real measurements and each energy of the peak from the results of Monte Carlo simulation. The energy resolutions and the values of the efficiency were also evaluated. From the measurement, the alpha imaging detector showed an energy resolution of 16.7% at 5.5 MeV and an efficiency of 27.9%. The tests of resolution and efficiency demonstrate that the alpha imaging detector is correctly calibrated using a single standard source. Further study will include evaluating the effectiveness of the proposed method and the application of the alpha imaging detector for quantitative analysis.