To understand the forward particle production in hadronic collisions, the Large Hadron Collider forward (LHCf) experiment has performed measurements at the LHC under various collision condition. The data of particle production at the highest accelerator energy are expected to im- prove the interpretation of the cosmic-ray air shower observation data, and hence to improve the knowledge of the cosmic-ray origin. Brief overview of the LHCf results obtained from the proton-proton collisions at √s=0.9, 2.76, 7 and 13 TeV and results from the proton-lead collisions at √s=5.02 TeV are presented. To explore the lower collision energy, √s=510 GeV, preparation of a new experiment the Relativistic Heavy Ion Collider forward (RHICf) is on going. Physics motivations and status of the RHICf are also presented.