To provide an automatic chuck greasing device in a crankshaft miller capable of ensuring chuck greasing without missing its timing and preventing failure to remove excess grease by wiping. In a crankshaft miller (1) which cuts, using a rotary cutter (7), a workpiece (2) held by a chuck (3), the automatic greasing device includes: a grease supply device (25) for supplying grease to sliding parts inside a chuck (3) including one between a chuck body (3a) and a chuck jaw (3b) in response to a greasing command signal outputted by a greasing command signal output unit (35) which has received a rotary cutter replacement command signal as a trigger signal from a rotary cutter replacement command signal output unit (33); and a notification means (30a, 30b) for notifying that a cutter (7) needs replacement in response to a notification command signal outputted by a notification command signal output unit (36) which has received the rotary cutter replacement command signal as the trigger signal from a rotary cutter replacement command signal output unit (33).