The optical parity checker plays an important role in error detection and correction for high-speed, large-capacity, complex digital optical communication networks, which can be employed to detect and correct the error bits by using a specific coding theory such as introducing error-detecting and correcting codes in communication channels. In this paper, we report an integrated silicon photonic circuit that is capable of implementing the parity checking for binary string with an arbitrary number of bits. The proposed parity checker consisting of parallel cascaded N micro-ring resonators (MRRs) is based on directed logic scheme, which means that the operands applied to MRRs to control the switching states of the MRRs are electrical signals, the operation signals are optical signals, and the final operation results are obtained at the output ports in the form of light. A 3-bit parity checker with an operation speed of 10 kbps, fabricated on a silicon-on-insulator (SOI) platform using a standard commercial complementary metal-oxide-semiconductor (CMOS) process, was experimentally and successfully demonstrated.