An encoder includes one or more encoder heads, one signal processing unit, a connector unit. The one or more encoder heads detect relative displacement of the one or more encoder heads and one or more scales. The one signal processing unit processes one or more electric signals output from the one or more encoder heads. The connector unit is located on the side of the one or more encoder heads between the one or more encoder heads and the signal processing unit and which groups together the one or more electric signals output from the one or more encoder heads.