An electromagnetic doorlock with button detection and power saving device includes an electromagnet assembly and a corresponding adsorption assembly. The electromagnet assembly is connected to a button detection module and the adsorption assembly has a pressing member to abut the button detection module. When the door is closed, the electromagnet assembly with electromagnetic attraction attracts the adsorption assembly and the pressing member presses the button detection module. That is, the electromagnetic doorlock usually stays in a low-energy attraction state; however, when the button detection module is triggered, the electromagnetic doorlock returns to a normal lock state for achieving power saving effect and control of the external force detection improvement.