To compare the safety and efficacy of Botulax Inj.®(Botulinum toxin type A, Hugel, South Korea) with Botox Inj.® (Botulinum toxin type A, Allergan, USA) in the treatment of cerebral palsy in children.

Inclusion Criteria:

1. Children patients ages from 2years old to 10years old.
2. Patients who diagnosed with cerebral palsy.
3. Patients who diagnosed as Gross Motor Function Classification System level I, II, or III
4. Patients who diagnosed as dynamic equinus foot deformity
5. Patients who agree with participation and signed to written agreement by substitute. (Get a signature from children patients if possible)deformity and I, II or III level of Gross Motor Function Classification System

Exclusion Criteria:

1. Patients who had previous injection of other botulinum toxin products in 3 months
2. Patients with hypersensitivity history to botulinum toxin products previously
3. Patients with neuromuscular junction disorder (myasthenia gravis, Lambert- Eaton syndrome, or amyotrophic lateral sclerosis, etc.)
4. Those who have severe cardiovascular, kidney, liver, or respiratory diseases
5. Those who are taking anticoagulant drugs or have bleeding disorder.
6. Pratients with treatment of following drugs: Anticonvulsants, tranquilizers, narcotics, aminoglycoside antibiotics, muscle relaxtants like baclofen, blockers of parasympathetic nervous system, and levodopa.
7. Patients who had history of surgery, plan to have surgery on legs, foot, or ankle.
8. Patients who have evidence of fixed contractures regarding to Investigator
9. Patients who have difference between two legs over 5cm
10. Patients with severe athetoid movement
11. Patients who had other treatments related to dynamic equinus foot deformity, such as alcohol injection or muscle relaxants
12. Those who were not enrolled in other studies within 30 days, or were not paseed over 5 times of half life for clinical trial drugs.
13. Patients who have possibility to take prevented drugs
14. Subjects who are not eligible for this study based on investigator's judgement