A work machine comprising: a work implement attached to a machine main body ; an operation sensor that detects an operation of the work implement by an operator; a pressure sensor that detects a pressure on a hydraulic actuator that drives the work implement ; a posture sensor that detects a posture of the work implement ; an antenna that is attached to the machine main body and receives satellite signals from a plurality of positioning satellites; a receiver configured to calculate a position of the machine main body on a basis of the satellite signals received by the antenna ; a first communication device that receives, from a base station, a correction signal used when the receiver calculates the position of the machine main body ; and a controller having a storage device storing a position of a construction target surface, and configured to calculate magnitude of a position difference in a height direction between the construction target surface and the work implement on a basis of the position of the construction target surface stored in the storage device , the position of the machine main body calculated by the receiver , and the posture of the work implement detected by the posture sensor , characterized in that the controller being configured to record, in the storage device , snapshot data of information about the operation sensor , the pressure sensor , the posture sensor , the receiver , and the first communication device in a predetermined period determined based on a time at which the magnitude of the position difference exceeds a predetermined value when the magnitude of the position difference exceeds the predetermined value, and diagnose a cause of the magnitude of the position difference exceeding the predetermined value, on a basis of the snapshot data. a work implement attached to a machine main body ; an operation sensor that detects an operation of the work implement by an operator; a pressure sensor that detects a pressure on a hydraulic actuator that drives the work implement ; a posture sensor that detects a posture of the work implement ; an antenna that is attached to the machine main body and receives satellite signals from a plurality of positioning satellites; a receiver configured to calculate a position of the machine main body on a basis of the satellite signals received by the antenna ; a first communication device that receives, from a base station, a correction signal used when the receiver calculates the position of the machine main body ; and a controller having a storage device storing a position of a construction target surface, and configured to calculate magnitude of a position difference in a height direction between the construction target surface and the work implement on a basis of the position of the construction target surface stored in the storage device , the position of the machine main body calculated by the receiver , and the posture of the work implement detected by the posture sensor , characterized in that the controller being configured to record, in the storage device , snapshot data of information about the operation sensor , the pressure sensor , the posture sensor , the receiver , and the first communication device in a predetermined period determined based on a time at which the magnitude of the position difference exceeds a predetermined value when the magnitude of the position difference exceeds the predetermined value, and diagnose a cause of the magnitude of the position difference exceeding the predetermined value, on a basis of the snapshot data. <EOS>