A loom heald-frame height adjusting apparatus according to the invention includes a support base (51, 61, 71), an adjusting mechanism (52, 62), and an ascending-descending member (53, 63, 63', 73). The support base (51, 61, 71) includes a setup portion (51 d, 61 d) and a guiding portion (51 a, 62a), the setup portion (51 d, 61 d) enabling the support base (51, 61, 71) to be mounted on a heald frame (10), and the guiding portion (51 a, 62a) extending upward from the setup portion (51 d, 61 d) in a state where the support base (51, 61, 71) is mounted on the heald frame (10). The adjusting mechanism (52, 62) includes an adjusting portion (52a, 62a) and a shift portion (52b, 62b). The adjusting portion (52a, 62a) is supported by the support base (51,61,71) and includes a screw portion. The shift portion (52b, 62b) is allowed to be shifted in the direction in which the guiding portion (51 a, 62a) extends and screwed on the screw portion of the adjusting portion (52a, 62a). The ascending-descending member (53, 63, 63', 73) includes a support portion and a hook portion (53a). The support portion is supported by the shift portion (52b, 62b) of the adjusting mechanism (52, 62). The hook portion (53a) is capable of hooking a downward-facing surface of the frame stave (11).