Spectrally encoded microscopy is a new reflecting microscopic imaging technique in which a diffraction grating is used to illuminate different positions on the sample with different wavelengths. A spectrally encoded microscopic imaging system is built, and it is based on a swept source at a sweeping rate of 50 kHz. In order to detect the weak light backscattered from the sample without a post-amplifier used, balanced detection is employed. The lateral resolution of the device is improved from 13.93 mm to 5.52 mm by imaging a USAF-1951 resolution target. The images of onion cells show that the signal-to-noise ratio (SNR) increases from 15.07 dB to 22.6 dB by balanced detection, demonstrating the capability of the method to improve both of the lateral resolution and SNR of the system. Images of in vitro swine gastric pits are presented to demonstrate tissue imaging capability of the technique. The work is useful for developing corresponding devices for potential clinical applications.