A trigger tension adjuster for use with a factory made trigger assembly which includes a trigger housing on which a trigger is pivotally mounted with a shoulder on the trigger accessible within the housing. The adjuster to be added to the trigger assembly includes a mounting block which has a front portion contoured to abut the rear and interior surfaces of the housing sidewalls and a rear shelf-like portion which will extend in spaced relationship above the trigger shoulder. The mounting block is secured to the housing and a spring biased plunger is threaded through the shelf-like portion so that the plunger is in engagement with the shoulder of the trigger. Thus, the weight of the trigger pull is controlled solely by the compression of the spring biasing the plunger against the trigger shoulder. When the depth of the plunger assembly is properly set, a set screw through the mounting block permits the user to secure the plunger at the appropriate depth. Thus, in the field, to adjust the trigger pull, the user need only loosen the set screw, rotate the plunger assemlby in its threads until the desired tension is attained and retighten the set screw.