A damping force adjustable shock absorber includes an electromagnetic damping force adjustment device (17) having a damping force adjustment valve (18), and a solenoid (33) configured to variably adjust the damping force. The solenoid includes a coil (39) configured to generate a magnetic force by power supply, a movable iron core (43) located on an inner peripheral side of the coil, an anchor member (40) configured to attract the movable iron core. The movable iron core includes a thick cylindrical portion (43A) and a taper cylindrical portion (43B). The thick cylindrical portion includes a fixation hole (43A1) in which a shaft portion (44) is fixed. The taper cylindrical portion has an inner peripheral surface flaring so as to define a taper shape. A recessed portion (43A2) is formed around the fixation hole. The recessed portion allows hydraulic fluid to flow in an axial direction of the movable iron core.