p38 mitogen‐activated protein kinase (MAPK) is a member of the serine/threonine kinases and is activated in response to stress stimuli, such as cytokines, ultraviolet irradiation, heat shock, and osmotic shock. We revealed in a previous report that p62/SQSTM1, known to participate in proteasomal or autophagosomal protein degradation and cytokine receptor signal transduction pathways, binds to p38 to regulate specifically. Herein, we describe the improvement of the photoaffinity‐thiol linker of our SPR imaging platform, which enabled us to determine the binding site of p62 to p38. SPR imaging experiments using a new photoaffinity linker 2 to immobilize the peptides derived from p62 on gold substrate indicate that the domain comprising amino acids 164–190 of p62 binds to p38 directly. These SPR analysis data and empirical biologic data reveal that the binding site of p62 to p38 is the domain corresponding to 173–182.