PURPOSE: To provide a connection of a hard synthetic resin pipe which is strengthened to have durability without any troubles of exfoliation, water leakage, etc.

CONSTITUTION: A connection 13 of a hard synthetic resin pipe 11 is protected by connectively enclosing and overlapping the connection 13 formed of one end of the hard synthetic resin pipe 11 connectively inserted into a synthetic resin joint 12 having the inner diameter approximately equal to the outer diameter of one end of the hard synthetic resin pipe 11 with a joint protecting pipe 10 having one end having the inner diameter approximately equal to the outer diameter of the synthetic resin pipe 11 and the other end having the inner diameter approximately equal to the outer diameter synthetic resin joint 12.