To provide a motor-driven cutting tool, easily positioning and locking a support member supporting a base, and simply and quickly adjusting the position of the base with good operational feeling.

A reciprocating saw (a motor-driven cutting tool) 1 includes: a reciprocating saw blade 4; the support member 14 fitted to a body 2 to move forward and backward; and the base 15 fitted to the tip of the support member 14. A plurality of engagement holes 14b are formed in the direction of moving forward and backward on the support member 14, and the position adjusting member 17 including an engagement member 18 having: a plurality of engaging projection parts 18a selectively engaged with one of the engagement holes 14b; and a locking member (a lock part) fitted to a fitting hole formed in the body 2, is rotatably provided on the body 2.