an incline angle adjustable stair climbing machine includes a base frame , a tilting seat pivotally mounted at the base frame , a tilting seat adjuster for adjusting an incline angle of the tilting seat relative to the base frame , a staircase mounted at the tilting seat and including a plurality of tread boards biasable relative to the tilting seat , and a tread board adjuster mounted at the tilting seat for adjusting a biasing angle of the tilting seat to maintain the plurality of tread boards constantly horizontal for enabling a user to conduct stair - climbing exercises at different climb gradients while maintaining good posture .