A lubricant supplying device includes: lubricant; a supplying member; a housing case; a pushing mechanism that includes a pair of swing members supported swingably in the housing case and a biasing unit urging the pair of swing members to swing; and a remaining amount detecting unit that detects that a remaining amount of the lubricant is equal to or smaller than a predetermined amount. The remaining amount detecting unit includes: first detection members provided at respective positions different from respective sliding areas of the member on which the swing members slide, on which sliding areas the respective swing members slide, and second detection members attached to the respective swing members such that the second detection members abut or face the respective first detection members when swing postures of the respective swing members reach respective swing postures corresponding to that the remaining amount of the lubricant is the predetermined amount.