A hand tool having an adjustable head with a joint lock mechanism comprises a head having a rear end and a handle having a front end pivotally coupled to the rear end of the head. The handle has a first aperture longitudinally extending at the front end thereof and a second aperture is formed perpendicularly intersecting the first aperture. The joint lock mechanism is disposed between the rear end of the head and the front end of the handle and further comprises: a first engaging device disposed at the rear end of the head; a second engaging device received in the first aperture, the second engaging device having a front end and a rear end; a pull button received in the second aperture; and a first elastic device received in the first aperture such that the second engaging device is provided with a forward force to engage the front end of the second engaging device with the first engaging device; characterised in that: the push button is formed with a through hole and provided with a first engaging portion being disposed beneath the through hole; the second engaging device passes through the push button and abuts against the first elastic device; the second engaging device is disposed with a second engaging portion and a second elastic device is disposed at the bottom of the push button such that the push button is provided with an upward force to engage the first engaging portion with the second engaging portion.