The utility model discloses an adjustable spanner suitable for a round nut with an end surface pinhole or a lateral surface pinhole. A guiding groove is arranged on the front lateral surface of a short arm of a T-shaped hand-hold handle, two guiding bars are respectively installed in the groove arranged at both sides, the guiding bars are respectively matched with an adjustable leading screw, the right and the left thread of which rotate oppositely, both ends of the adjustable leading screw are respectively installed on the front lateral surface of the short arm of the T-shaped hand-hold handle through an end cover, thereby forming a running fit with the end cover, guiding grooves are evenly arranged at the extending direction of the two guiding bars, pin claw seats which can be moved in the guiding grooves and can be vertically matched with the guiding grooves are installed in the grooves, knurled nuts of the pin claw seats can be locked at any position of the guiding grooves of the guiding bars, and detachable pin claws are evenly installed at the front ends and on the inner lateral surfaces of the pin claw seats. The distance between the pin claws is adjusted, to be applied to the rotary twisting of round nuts of different specifications of the outer diameter; in addition, the pin claws and the pin claw seats are coupled both at horizontal and vertical directions, thus the adjustable spanner is not only suitable for the rotary twisting of the round nuts with the end surface pinholes, but also suitable for the rotary twisting of the round nuts with the lateral surface pinholes.