An attachment monitoring system comprising: a working machine (10; 10A) that includes a working arm; attachments (15; 15A) each of which is attached to a leading end part of the working arm so as to be driven by a fluid pressure; a measurement unit (16; 16A; 16B; 16C) that is provided to measure at least one of a vibration and the fluid pressure when each of the attachments (15; 15A) identified based on individual identifying information is driven; a terminal device that is provided in the working machine (10; 10A), the terminal device acquiring measured results of the measurement unit (16; 16A; 16B; 16C); characterized in that the attachment monitoring system further comprises a server device that collects the measured results of the respective attachments (15; 15A) from the terminal device, and analyzes operation states of the respective attachments (15; 15A) based on the collected measured results, and wherein the working machine (10; 10A) further includes: a fluid pressure generating device that generates the fluid pressure, and a first supply/discharge passage that is a supply/discharge passage of a fluid from the fluid pressure generating device, each of the attachments (15; 15A) includes a second supply/discharge passage that is a supply/discharge passage of the fluid to the corresponding attachment (15; 15A), and the measurement unit (16; 16A; 16B; 16C) is provided between the first supply/discharge passage and the second supply/discharge passage, and connects the first supply/discharge passage and the second supply/discharge passage. a working machine (10; 10A) that includes a working arm; attachments (15; 15A) each of which is attached to a leading end part of the working arm so as to be driven by a fluid pressure; a measurement unit (16; 16A; 16B; 16C) that is provided to measure at least one of a vibration and the fluid pressure when each of the attachments (15; 15A) identified based on individual identifying information is driven; a terminal device that is provided in the working machine (10; 10A), the terminal device acquiring measured results of the measurement unit (16; 16A; 16B; 16C); characterized in that the attachment monitoring system further comprises a server device that collects the measured results of the respective attachments (15; 15A) from the terminal device, and analyzes operation states of the respective attachments (15; 15A) based on the collected measured results, and wherein the working machine (10; 10A) further includes: a fluid pressure generating device that generates the fluid pressure, and a first supply/discharge passage that is a supply/discharge passage of a fluid from the fluid pressure generating device, a fluid pressure generating device that generates the fluid pressure, and a first supply/discharge passage that is a supply/discharge passage of a fluid from the fluid pressure generating device, each of the attachments (15; 15A) includes a second supply/discharge passage that is a supply/discharge passage of the fluid to the corresponding attachment (15; 15A), and the measurement unit (16; 16A; 16B; 16C) is provided between the first supply/discharge passage and the second supply/discharge passage, and connects the first supply/discharge passage and the second supply/discharge passage.