There is provide a ratchet-type tensioner that enables to readily disengage a plunger from a ratchet element in maintaining an engine, that engages the plunger reliably with the ratchet element in operating the engine so as to reduce flapping noise, and that prevents seizure of the plunger. A ratchet releasing mechanism X configured to release an engagement of the ratchet teeth 151 of the ratchet element 150 with the rack teeth 122 of the plunger 120 by means of a tool pin T includes a ratchet releasing pin guide hole 114 formed through the housing body 110 to insert a pin edge portion T1 of the tool pin T into a plunger-side edge region of the ratchet element 150 and a ratchet releasing pin engaging hole 155 formed in the plunger-side edge region of the ratchet element 150 to guide and engage the pin edge portion T1 of the tool pin T inserted from the ratchet releasing pin guide hole 114.